Zoom lens system, imaging device and camera

ABSTRACT

A high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and the conditions: −2.0&lt;f 2 /f W &lt;−1.1, f T /f W &gt;6.0 and ω W ≧30 (f 2 : a composite focal length of the second lens unit, f T : a focal length of the entire system at a telephoto limit, f W : a focal length of the entire system at a wide-angle limit, ω W : a half view angle at a wide-angle limit) are satisfied; an imaging device; and a camera are provided.

TECHNICAL FIELD

The present invention relates to a zoom lens system, an imaging device and a camera. In particular, the present invention relates to: a high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner; an imaging device employing the zoom lens system; and a thin and compact camera employing the imaging device.

BACKGROUND ART

There are extremely strong demands for size reduction and performance improvement in digital still cameras and digital video cameras (simply referred to as digital cameras, hereinafter) having an image sensor for performing photoelectric conversion. In particular, from a convenience point of view, digital cameras are strongly requested that employ a zoom lens system having a high zooming ratio and still covering a wide focal-length range from a wide angle condition to a highly telephoto condition. On the other hand, in recent years, zoom lens systems are also desired that have a wide angle range where the photographing field is large.

As zoom lens systems having a high zooming ratio and zoom lens systems having a wide angle range as described above, various kinds of zoom lenses having a four-unit construction of positive, negative, positive and positive have conventionally been proposed, which each comprises, in order from the object side to the image side, a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power.

Japanese Laid-Open Patent Publication No. 2008-146016 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which at the time of magnification change from a wide-angle limit to a telephoto limit, at least a first lens unit, a second lens unit, and a third lens unit are moved and thereby the intervals between the respective lens units are changed, the second lens unit is composed of at most three lenses, and the relation between the ratio of the values of lateral magnification of the second lens unit at a telephoto limit and a wide-angle limit and the ratio of the values of lateral magnification of the third lens unit at a telephoto limit and a wide-angle limit is set forth.

Japanese Laid-Open Patent Publication No. 2008-122880 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, and having a zooming ratio of 3 to 12, in which a second lens unit is composed of at most three lenses, a bi-concave negative lens is arranged on the most object side in the second lens unit, and the shape factor of the bi-concave negative lens is set forth.

Japanese Laid-Open Patent Publication No. 2008-122879 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is composed of a negative lens and a positive lens, and the shape factor of the positive lens is set forth.

Japanese Laid-Open Patent Publication No. 2008-052116 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is composed of a positive lens and a negative lens, a second lens unit is composed of, in order from the object side, a negative lens and a positive lens, and a refractive index and an Abbe number of the negative lens in the second lens unit are set forth.

Japanese Laid-Open Patent Publication No. 2008-052113 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, and having a zooming ratio of 3.8 to 10, in which a second lens unit includes a bi-concave negative lens on the most object side, the entire second lens unit is composed of at most two negative lenses and a positive lens, and the shape factor of the bi-concave negative lens is set forth.

Japanese Laid-Open Patent Publication No. 2008-052110 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a second lens unit is composed of, in order from the object side, a negative lens and a positive lens, and a refractive index and an Abbe number of the positive lens are set forth.

Japanese Laid-Open Patent Publication No. 2007-328178 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is composed of, in order from the object side, a negative lens and a positive lens, a second lens unit is composed of, in order from the object side, a negative lens and a positive lens, a third lens unit is composed of at most three lenses including a positive lens and a negative lens, and a fourth lens unit is composed of a positive lens.

Japanese Laid-Open Patent Publication No. 2007-256452 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a third lens unit is composed of, in order from the object side, a first positive lens, a second bi-concave negative lens, and a third negative lens, and at the time of magnification change, the interval between a first lens unit and a second lens unit is greater and the interval between the second lens unit and the third lens unit is smaller at a telephoto limit than at a wide-angle limit.

Japanese Laid-Open Patent Publication No. 2007-240747 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is composed of, in order from the object side, two lenses, i.e., a negative lens and a positive lens; a second lens unit is composed of, in order from the object side, two lenses, i.e., a negative lens and a positive lens; a third lens unit is composed of, in order from the object side, three lenses, i.e., a positive lens, a positive lens, and a negative lens; a fourth lens unit is composed of a positive lens; at the time of magnification change, the interval between the first lens unit and the second lens unit is greater at a telephoto limit than at a wide-angle limit, and the third lens unit is located closer to the object side so that the interval between the third lens unit and the second lens unit decreases; a brightness diaphragm, which moves in the direction along the optical axis at the time of magnification change, is arranged between the second lens unit and the third lens unit; and the brightness diaphragm is located closer to the object side at a telephoto limit than at a wide-angle limit.

Japanese Laid-Open Patent Publication No. 2007-171371 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is located closer to the object side at a telephoto limit than at a wide-angle limit; the interval between the first lens unit and a second lens unit is greater, the interval between the second lens unit and a third lens unit is smaller, and the interval between the third lens unit and a fourth lens unit is greater at a telephoto limit than at a wide-angle limit; the first lens unit is composed of a negative lens and a positive lens; the second lens unit is composed of, in order from the object side to the image side, a negative lens and a positive lens; and the ratio between the focal length of the negative lens in the second lens unit or the focal length of the second lens unit, and the focal length of the entire lens system at a wide-angle limit is set forth.

Japanese Laid-Open Patent Publication No. 2008-172321 discloses an imaging device comprising: a zoom lens which includes the above-mentioned four-unit construction of positive, negative, positive and positive, and performs zooming from a wide-angle limit to a telephoto limit with the intervals between a plurality of lens units being varied; an image sensor; and an image recovery unit, in which the relations among the maximum length of the zoom lens along the optical axis from its most-object-side refractive surface to its imaging surface, the focal lengths of the entire system at a wide-angle limit and a telephoto limit, the minimum F-number at a telephoto limit, and the half of the diagonal length of an effective imaging range on the imaging surface, are set forth.

CITATION LIST Patent Literature

-   [PTL 1] Japanese Laid-Open Patent Publication No. 2008-146016 -   [PTL 2] Japanese Laid-Open Patent Publication No. 2008-122880 -   [PTL 3] Japanese Laid-Open Patent Publication No. 2008-122879 -   [PTL 4] Japanese Laid-Open Patent Publication No. 2008-052116 -   [PTL 5] Japanese Laid-Open Patent Publication No. 2008-052113 -   [PTL 6] Japanese Laid-Open Patent Publication No. 2008-052110 -   [PTL 7] Japanese Laid-Open Patent Publication No. 2007-328178 -   [PTL 8] Japanese Laid-Open Patent Publication No. 2007-256452 -   [PTL 9] Japanese Laid-Open Patent Publication No. 2007-240747 -   [PTL 10] Japanese Laid-Open Patent Publication No. 2007-171371 -   [PTL 11] Japanese Laid-Open Patent Publication No. 2008-172321

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Each of the zoom lenses disclosed in the respective patent literatures is miniaturized to such an extent that it can be applied to a thin and compact digital camera, but cannot meet the recent demands in terms of achieving a good balance between the view angle at a wide-angle limit and the zooming ratio.

The object of the present invention is to provide: a high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner; an imaging device employing the zoom lens system; and a thin and compact camera employing the imaging device.

Solution to the Problems

(I) One of the above-described objects is achieved by the following zoom lens system. That is, the present invention relates to:

a zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein

the first lens unit is composed of at most two lens elements,

the second lens unit is composed of two lens elements,

the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and

the following conditions (2-2), (b-1) and (a-2) are satisfied:

−2.0<f ₂ /f _(W)<−1.1  (2-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)>30  (a-2)

where,

f₂ is a composite focal length of the second lens unit,

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

One of the above-described objects is achieved by the following imaging device. That is, the present invention relates to:

an imaging device capable of outputting an optical image of an object as an electric image signal, comprising:

a zoom lens system that forms an optical image of the object; and

an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein

the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein

the first lens unit is composed of at most two lens elements,

the second lens unit is composed of two lens elements,

the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and

the following conditions (2-2), (b-1) and (a-2) are satisfied:

−2.0<f ₂ /f _(W)<−1.1  (2-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)≧30  (a-2)

where,

f₂ is a composite focal length of the second lens unit,

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

One of the above-described objects is achieved by the following camera. That is, the present invention relates to:

a camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:

an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein

the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein

the first lens unit is composed of at most two lens elements,

the second lens unit is composed of two lens elements,

the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and

the following conditions (2-2), (b-1) and (a-2) are satisfied:

−2.0<f ₂ /f _(W)<−1.1  (2-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)>30  (a-2)

where,

f₂ is a composite focal length of the second lens unit,

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

(II) One of the above-described objects is achieved by the following zoom lens system. That is, the present invention relates to:

a zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein

the first lens unit is composed of at most two lens elements,

the second lens unit is composed of two lens elements,

the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and

the following conditions (3-2), (b-1) and (a-2) are satisfied:

1.1<(β_(2T)/β_(2W))/(β_(3T)/β_(3W))<5.2  (3-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)≧30  (a-2)

where,

β_(2T) is a lateral magnification of the second lens unit at a telephoto limit,

β_(2W) is a lateral magnification of the second lens unit at a wide-angle limit,

β_(3T) is a lateral magnification of the third lens unit at a telephoto limit,

β_(3W) is a lateral magnification of the third lens unit at a wide-angle limit,

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

One of the above-described objects is achieved by the following imaging device. That is, the present invention relates to:

an imaging device capable of outputting an optical image of an object as an electric image signal, comprising:

a zoom lens system that forms an optical image of the object; and

an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein

the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein

the first lens unit is composed of at most two lens elements,

the second lens unit is composed of two lens elements,

the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and

the following conditions (3-2), (b-1) and (a-2) are satisfied:

1.1<(β_(2T)/β_(2W))/(β_(3T)/β_(3W))<5.2  (3-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)>30  (a-2)

where,

β_(2T) is a lateral magnification of the second lens unit at a telephoto limit,

β_(2W) is a lateral magnification of the second lens unit at a wide-angle limit,

β_(3T) is a lateral magnification of the third lens unit at a telephoto limit,

β_(3W) is a lateral magnification of the third lens unit at a wide-angle limit,

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

One of the above-described objects is achieved by the following camera. That is, the present invention relates to:

a camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:

an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein

the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein

the first lens unit is composed of at most two lens elements,

the second lens unit is composed of two lens elements,

the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and

the following conditions (3-2), (b-1) and (a-2) are satisfied:

1.1<(β_(2T)/β_(2W))/(β_(3T)/β_(3W))<5.2  (3-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)≧30  (a-2)

where,

β_(2T) is a lateral magnification of the second lens unit at a telephoto limit,

β_(2W) is a lateral magnification of the second lens unit at a wide-angle limit,

β_(3T) is a lateral magnification of the third lens unit at a telephoto limit,

β_(3W) is a lateral magnification of the third lens unit at a wide-angle limit,

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

(III) One of the above-described objects is achieved by the following zoom lens system. That is, the present invention relates to:

a zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein

the first lens unit is composed of at most two lens elements,

the second lens unit is composed of two lens elements,

the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and

the following conditions (4-2), (b-1) and (a-2) are satisfied:

0.9<M ₁ /M ₃<3.0  (4-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)>30  (a-2)

where,

M₁ is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),

M₃ is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

One of the above-described objects is achieved by the following imaging device. That is, the present invention relates to:

an imaging device capable of outputting an optical image of an object as an electric image signal, comprising:

a zoom lens system that forms an optical image of the object; and

an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein

the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein

the first lens unit is composed of at most two lens elements,

the second lens unit is composed of two lens elements,

the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and

the following conditions (4-2), (b-1) and (a-2) are satisfied:

0.9<M ₁ /M ₃<3.0  (4-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)>30  (a-2)

where,

M₁ is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),

M₃ is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

One of the above-described objects is achieved by the following camera. That is, the present invention relates to:

a camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:

an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein

the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein

the first lens unit is composed of at most two lens elements,

the second lens unit is composed of two lens elements,

the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and

the following conditions (4-2), (b-1) and (a-2) are satisfied:

0.9<M ₁ /M ₃<3.0  (4-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)>30  (a-2)

where,

M₁ is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),

M₃ is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

Effects of the Invention

According to the present invention, it is possible to provide: a high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner; an imaging device employing the zoom lens system; and a thin and compact camera employing the imaging device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-1 (Example I-1).

FIG. 2 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-1.

FIG. 3 is a lateral aberration diagram of a zoom lens system according to Example I-1 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 4 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-2 (Example I-2).

FIG. 5 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-2.

FIG. 6 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-3 (Example I-3).

FIG. 7 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-3.

FIG. 8 is a lateral aberration diagram of a zoom lens system according to Example I-3 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 9 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-4 (Example I-4).

FIG. 10 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-4.

FIG. 11 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-5 (Example I-5).

FIG. 12 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-5.

FIG. 13 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-6 (Example I-6).

FIG. 14 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-6.

FIG. 15 is a schematic construction diagram of a digital still camera according to Embodiment I-7.

FIG. 16 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-1 (Example II-1).

FIG. 17 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-1.

FIG. 18 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-2 (Example II-2).

FIG. 19 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-2.

FIG. 20 is a lateral aberration diagram of a zoom lens system according to Example II-2 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 21 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-3 (Example II-3).

FIG. 22 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-3.

FIG. 23 is a lateral aberration diagram of a zoom lens system according to Example II-3 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 24 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-4 (Example II-4).

FIG. 25 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-4.

FIG. 26 is a lateral aberration diagram of a zoom lens system according to Example II-4 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 27 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-5 (Example II-5).

FIG. 28 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-5.

FIG. 29 is a lateral aberration diagram of a zoom lens system according to Example II-5 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 30 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-6 (Example II-6).

FIG. 31 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-6.

FIG. 32 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-7 (Example II-7).

FIG. 33 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-7.

FIG. 34 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-8 (Example II-8).

FIG. 35 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-8.

FIG. 36 is a schematic construction diagram of a digital still camera according to Embodiment II-9.

FIG. 37 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-1 (Example III-1).

FIG. 38 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-1.

FIG. 39 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-2 (Example III-2).

FIG. 40 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-2.

FIG. 41 is a lateral aberration diagram of a zoom lens system according to Example III-2 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 42 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-3 (Example III-3).

FIG. 43 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-3.

FIG. 44 is a lateral aberration diagram of a zoom lens system according to Example III-3 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 45 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-4 (Example III-4).

FIG. 46 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-4.

FIG. 47 is a lateral aberration diagram of a zoom lens system according to Example III-4 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 48 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-5 (Example III-5).

FIG. 49 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-5.

FIG. 50 is a lateral aberration diagram of a zoom lens system according to Example III-5 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.

FIG. 51 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-6 (Example III-6).

FIG. 52 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-6.

FIG. 53 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-7 (Example III-7).

FIG. 54 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-7.

FIG. 55 is a schematic construction diagram of a digital still camera according to Embodiment III-8.

EMBODIMENTS OF THE INVENTION Embodiments I-1 to I-6

FIGS. 1, 4, 6, 9, 11 and 13 are lens arrangement diagrams of zoom lens systems according to Embodiments I-1 to I-6, respectively.

Each of FIGS. 1, 4, 6, 9, 11 and 13 shows a zoom lens system in an infinity in-focus condition. In each Fig., part (a) shows a lens configuration at a wide-angle limit (in the minimum focal length condition: focal length f_(W)), part (b) shows a lens configuration at a middle position (in an intermediate focal length condition: focal length f_(M)=√(f_(W)*f_(T))), and part (c) shows a lens configuration at a telephoto limit (in the maximum focal length condition: focal length f_(T)). Further, in each Fig., an arrow of straight or curved line provided between part (a) and part (b) indicates the movement of each lens unit from a wide-angle limit through a middle position to a telephoto limit. Moreover, in each Fig., an arrow imparted to a lens unit indicates focusing from an infinity in-focus condition to a close-object in-focus condition. That is, the arrow indicates the moving direction at the time of focusing from an infinity in-focus condition to a close-object in-focus condition.

The zoom lens system according to each embodiment, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having positive optical power, and a fourth lens unit having positive optical power. Then, in zooming, the individual lens units move in a direction along the optical axis such that intervals between the lens units, that is, the interval between the first lens unit and the second lens unit, the interval between the second lens unit and the third lens unit, and the interval between the third lens unit and the fourth lens unit should all vary. In the zoom lens system according to each embodiment, since these lens units are arranged in the desired optical power configuration, high optical performance is maintained and still size reduction is achieved in the entire lens system.

Further, in FIGS. 1, 4, 6, 9, 11 and 13, an asterisk “*” imparted to a particular surface indicates that the surface is aspheric. In each Fig., symbol (+) or (−) imparted to the symbol of each lens unit corresponds to the sign of the optical power of the lens unit. In each Fig., the straight line located on the most right-hand side indicates the position of the image surface S. On the object side relative to the image surface S (that is, between the image surface S and the most image side lens surface of the fourth lens unit G4), a plane parallel plate P equivalent to an optical low-pass filter or a face plate of an image sensor is provided.

Further, in FIGS. 1, 4, 6, 9, 11 and 13, an aperture diaphragm A is provided on the most object side in the third lens unit G3. In zooming from a wide-angle limit to a telephoto limit at the time of image taking, the aperture diaphragm A moves along the optical axis integrally with the third lens unit G3.

As shown in FIG. 1, in the zoom lens system according to Embodiment I-1, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment I-1, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment I-1, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-1, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-1, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment I-1, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 4, in the zoom lens system according to Embodiment I-2, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment I-2, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment I-2, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. The fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-2, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the object side. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-2, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment I-2, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 6, in the zoom lens system according to Embodiment I-3, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.

In the zoom lens system according to Embodiment I-3, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment I-3, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-3, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-3, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment I-3, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 9, in the zoom lens system according to Embodiment I-4, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.

In the zoom lens system according to Embodiment I-4, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment I-4, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-4, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-4, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment I-4, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 11, in the zoom lens system according to Embodiment I-5, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment I-5, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment I-5, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-5, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-5, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment I-5, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 13, in the zoom lens system according to Embodiment I-6, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment I-6, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment I-6, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-6, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment I-6, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment I-6, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

In the zoom lens systems according to Embodiments I-1 to I-6, the first lens unit G1 comprises two lens elements, the second lens unit G2 comprises two lens elements, and the third lens unit G3 comprises three lens elements. Thus, the lens system has a short overall optical length (overall length of lens system).

In the zoom lens systems according to Embodiments I-1 to I-6, the first lens unit G1, in order from the object side to the image side, is composed of the negative meniscus lens element L1 with the convex surface facing the object side, and the positive lens element L2. These two lens elements are cemented with each other to constitute a cemented lens element. Thus, a compact lens system is realized. Further, such a construction permits favorable compensation of chromatic aberration.

In the zoom lens systems according to Embodiments I-1 to I-6, in the second lens unit G2, the third lens element L3, which is an object side lens element, has an aspheric surface. Therefore, aberrations, particularly distortion at a wide-angle limit, can be compensated more favorably. Further, in the third lens unit G3, the fifth lens element L5, which is an object side positive lens element, has an aspheric surface. Therefore, aberrations, particularly spherical aberration, can be compensated more favorably.

In the zoom lens systems according to Embodiments I-1 to I-6, the third lens unit G3 is composed of three lens elements, i.e., in order from the object side to the image side, the fifth lens element L5 having positive optical power, the sixth lens element L6 having negative optical power, and the seventh lens element L7 having positive optical power. The fifth lens element L5, which is an object side positive lens element, and the sixth lens element L6 are cemented with each other to constitute a cemented lens element. Therefore, axial aberration, which occurs in the positive lens element, is compensated in the negative lens element, and thus excellent optical performance is achieved with a small number of lens elements.

In the zoom lens systems according to Embodiments I-1 to I-6, the fourth lens unit G4 is composed of a single lens element, and the lens element has positive optical power. Thus, the lens system has a short overall optical length (overall length of lens system). Further, at the time of focusing from an infinite-distance object to a close-distance object, as shown in each Fig., the fourth lens unit G4 is drawn out to the object side so that rapid focusing is achieved easily.

Further, in the zoom lens systems according to Embodiments I-1 to I-6, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1, the second lens unit G2, the third lens unit G3, and the fourth lens unit G4 are moved individually along the optical axis so that zooming is achieved. Then, any lens unit among the first lens unit G1, the second lens unit G2, the third lens unit G3 and the fourth lens unit G4, or alternatively, a sub lens unit consisting of a part of a lens unit is moved in a direction perpendicular to the optical axis, so that image point movement caused by vibration of the entire system is compensated, that is, image blur caused by hand blurring, vibration and the like can be compensated optically.

When image point movement caused by vibration of the entire system is to be compensated, for example, the third lens unit G3 is moved in a direction perpendicular to the optical axis. Thus, image blur is compensated in a state that size increase in the entire zoom lens system is suppressed to realize a compact construction and that excellent imaging characteristics such as small decentering coma aberration and small decentering astigmatism are maintained.

In a case that a lens unit is composed of a plurality of lens elements, the above-mentioned sub lens unit consisting of a part of a lens unit indicates any one lens element or alternatively a plurality of adjacent lens elements among the plurality of lens elements.

Embodiments II-1 to II-8

FIGS. 16, 18, 21, 24, 27, 30, 32 and 34 are lens arrangement diagrams of zoom lens systems according to Embodiments II-1 to II-8, respectively.

Each of FIGS. 16, 18, 21, 24, 27, 30, 32 and 34 shows a zoom lens system in an infinity in-focus condition. In each Fig., part (a) shows a lens configuration at a wide-angle limit (in the minimum focal length condition: focal length f_(W)), part (b) shows a lens configuration at a middle position (in an intermediate focal length condition: focal length f_(M)=√(f_(W)*f_(T))), and part (c) shows a lens configuration at a telephoto limit (in the maximum focal length condition: focal length f_(T)). Further, in each Fig., an arrow of straight or curved line provided between part (a) and part (b) indicates the movement of each lens unit from a wide-angle limit through a middle position to a telephoto limit. Moreover, in each Fig., an arrow imparted to a lens unit indicates focusing from an infinity in-focus condition to a close-object in-focus condition. That is, the arrow indicates the moving direction at the time of focusing from an infinity in-focus condition to a close-object in-focus condition.

The zoom lens system according to each embodiment, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power; a second lens unit G2 having negative optical power; a third lens unit G3 having positive optical power; and a fourth lens unit having positive optical power. Then, in zooming, the individual lens units move in a direction along the optical axis such that intervals between the lens units, that is, the interval between the first lens unit and the second lens unit, the interval between the second lens unit and the third lens unit, and the interval between the third lens unit and the fourth lens unit should all vary. In the zoom lens system according to each embodiment, since these lens units are arranged in the desired optical power configuration, high optical performance is maintained and still size reduction is achieved in the entire lens system.

Further, in FIGS. 16, 18, 21, 24, 27, 30, 32 and 34, an asterisk “*” imparted to a particular surface indicates that the surface is aspheric. In each Fig., symbol (+) or (−) imparted to the symbol of each lens unit corresponds to the sign of the optical power of the lens unit. In each Fig., the straight line located on the most right-hand side indicates the position of the image surface S. On the object side relative to the image surface S (that is, between the image surface S and the most image side lens surface of the fourth lens unit G4), a plane parallel plate P equivalent to an optical low-pass filter or a face plate of an image sensor is provided.

Further, in FIGS. 16, 18, 21, 24, 27, 30, 32 and 34, an aperture diaphragm A is provided on the most object side in the third lens unit G3. In zooming from a wide-angle limit to a telephoto limit at the time of image taking, the aperture diaphragm A moves along the optical axis integrally with the third lens unit G3.

As shown in FIG. 16, in the zoom lens system according to Embodiment II-1, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment II-1, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment II-1, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a positive meniscus seventh lens element L7 with the convex surface facing the object side. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-1, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-1, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment II-1, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 18, in the zoom lens system according to Embodiment II-2, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment II-2, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment II-2, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-2, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-2, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment II-2, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 21, in the zoom lens system according to Embodiment II-3, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment II-3, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment II-3, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-3, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-3, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment II-3, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 24, in the zoom lens system according to Embodiment II-4, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.

In the zoom lens system according to Embodiment II-4, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment II-4, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. The fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-4, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the object side. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-4, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment II-4, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 27, in the zoom lens system according to Embodiment II-5, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.

In the zoom lens system according to Embodiment II-5, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment II-5, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-5, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-5, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment II-5, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 30, in the zoom lens system according to Embodiment II-6, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.

In the zoom lens system according to Embodiment II-6, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment II-6, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-6, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-6, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment II-6, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 32, in the zoom lens system according to Embodiment II-7, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment II-7, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment II-7, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-7, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-7, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment II-7, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 34, in the zoom lens system according to Embodiment II-8, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment II-8, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment II-8, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-8, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment II-8, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment II-8, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

In the zoom lens systems according to Embodiments II-1 to II-8, the first lens unit G1 comprises two lens elements, the second lens unit G2 comprises two lens elements, and the third lens unit G3 comprises three lens elements. Thus, the lens system has a short overall optical length (overall length of lens system).

In the zoom lens systems according to Embodiments II-1 to II-8, the first lens unit G1, in order from the object side to the image side, is composed of the negative meniscus lens element L1 with the convex surface facing the object side, and the positive lens element L2. These two lens elements are cemented with each other to constitute a cemented lens element. Thus, a compact lens system is realized. Further, such a construction permits favorable compensation of chromatic aberration.

In the zoom lens systems according to Embodiments II-1 to II-8, in the second lens unit G2, the third lens element L3, which is an object side lens element, has an aspheric surface. Therefore, aberrations, particularly distortion at a wide-angle limit, can be compensated more favorably. Further, in the third lens unit G3, the fifth lens element L5, which is an object side positive lens element, has an aspheric surface. Therefore, aberrations, particularly spherical aberration, can be compensated more favorably.

In the zoom lens systems according to Embodiments II-1 to II-8, the third lens unit G3 is composed of three lens elements, i.e., in order from the object side to the image side, the fifth lens element L5 having positive optical power, the sixth lens element L6 having negative optical power, and the seventh lens element L7 having positive optical power. The fifth lens element L5, which is an object side positive lens element, and the sixth lens element L6 are cemented with each other to constitute a cemented lens element. Therefore, axial aberration, which occurs in the positive lens element, is compensated in the negative lens element, and thus excellent optical performance is achieved with a small number of lens elements.

In the zoom lens systems according to Embodiments II-1 to II-8, the fourth lens unit G4 is composed of a single lens element, and the lens element has positive optical power. Thus, the lens system has a short overall optical length (overall length of lens system). Further, at the time of focusing from an infinite-distance object to a close-distance object, as shown in each Fig., the fourth lens unit G4 is drawn out to the object side so that rapid focusing is achieved easily.

Further, in the zoom lens systems according to Embodiments II-1 to II-8, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1, the second lens unit G2, the third lens unit G3, and the fourth lens unit G4 are moved individually along the optical axis so that zooming is achieved. Then, any lens unit among the first lens unit G1, the second lens unit G2, the third lens unit G3 and the fourth lens unit G4, or alternatively, a sub lens unit consisting of a part of a lens unit is moved in a direction perpendicular to the optical axis, so that image point movement caused by vibration of the entire system is compensated, that is, image blur caused by hand blurring, vibration and the like can be compensated optically.

When image point movement caused by vibration of the entire system is to be compensated, for example, the third lens unit G3 is moved in a direction perpendicular to the optical axis. Thus, image blur is compensated in a state that size increase in the entire zoom lens system is suppressed to realize a compact construction and that excellent imaging characteristics such as small decentering coma aberration and small decentering astigmatism are maintained.

In a case that a lens unit is composed of a plurality of lens elements, the above-mentioned sub lens unit consisting of a part of a lens unit indicates any one lens element or alternatively a plurality of adjacent lens elements among the plurality of lens elements.

Embodiments III-1 to III-7

FIGS. 37, 39, 42, 45, 48, 51 and 53 are lens arrangement diagrams of zoom lens systems according to Embodiments III-1 to III-7, respectively.

Each of FIGS. 37, 39, 42, 45, 48, 51 and 53 shows a zoom lens system in an infinity in-focus condition. In each Fig., part (a) shows a lens configuration at a wide-angle limit (in the minimum focal length condition: focal length f_(W)), part (b) shows a lens configuration at a middle position (in an intermediate focal length condition: focal length f_(M)=√(f_(W)*f_(T))), and part (c) shows a lens configuration at a telephoto limit (in the maximum focal length condition: focal length f_(T)). Further, in each Fig., an arrow of straight or curved line provided between part (a) and part (b) indicates the movement of each lens unit from a wide-angle limit through a middle position to a telephoto limit. Moreover, in each Fig., an arrow imparted to a lens unit indicates focusing from an infinity in-focus condition to a close-object in-focus condition. That is, the arrow indicates the moving direction at the time of focusing from an infinity in-focus condition to a close-object in-focus condition.

The zoom lens system according to each embodiment, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having positive optical power, and a fourth lens unit having positive optical power. Then, in zooming, the individual lens units move in a direction along the optical axis such that intervals between the lens units, that is, the interval between the first lens unit and the second lens unit, the interval between the second lens unit and the third lens unit, and the interval between the third lens unit and the fourth lens unit should all vary. In the zoom lens system according to each embodiment, since these lens units are arranged in the desired optical power configuration, high optical performance is maintained and still size reduction is achieved in the entire lens system.

Further, in FIGS. 37, 39, 42, 45, 48, 51 and 53, an asterisk “*” imparted to a particular surface indicates that the surface is aspheric. In each Fig., symbol (+) or (−) imparted to the symbol of each lens unit corresponds to the sign of the optical power of the lens unit. In each Fig., the straight line located on the most right-hand side indicates the position of the image surface S. On the object side relative to the image surface S (that is, between the image surface S and the most image side lens surface of the fourth lens unit G4), a plane parallel plate P equivalent to an optical low-pass filter or a face plate of an image sensor is provided.

Further, in FIGS. 37, 39, 42, 45, 48, 51 and 53, an aperture diaphragm A is provided on the most object side in the third lens unit G3. In zooming from a wide-angle limit to a telephoto limit at the time of image taking, the aperture diaphragm A moves along the optical axis integrally with the third lens unit G3.

As shown in FIG. 37, in the zoom lens system according to Embodiment III-1, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment III-1, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment III-1, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-1, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-1, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment III-1, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 39, in the zoom lens system according to Embodiment III-2, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment III-2, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment III-2, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-2, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-2, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment III-2, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 42, in the zoom lens system according to Embodiment III-3, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment III-3, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment III-3, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. The fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-3, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-3, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment III-3, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 45, in the zoom lens system according to Embodiment III-4, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.

In the zoom lens system according to Embodiment III-4, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment III-4, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. The fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-4, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the object side. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-4, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment III-4, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 48, in the zoom lens system according to Embodiment III-5, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.

In the zoom lens system according to Embodiment III-5, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment III-5, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-5, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-5, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment III-5, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 51, in the zoom lens system according to Embodiment III-6, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment III-6, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment III-6, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-6, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-6, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment III-6, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

As shown in FIG. 53, in the zoom lens system according to Embodiment III-7, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment III-7, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.

In the zoom lens system according to Embodiment III-7, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-7, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.

In the zoom lens system according to Embodiment III-7, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).

In the zoom lens system according to Embodiment III-7, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.

In the zoom lens systems according to Embodiments III-1 to III-7, the first lens unit G1 comprises two lens elements, the second lens unit G2 comprises two lens elements, and the third lens unit G3 comprises three lens elements. Thus, the lens system has a short overall optical length (overall length of lens system).

In the zoom lens systems according to Embodiments III-1 to III-7, the first lens unit G1, in order from the object side to the image side, is composed of the negative meniscus lens element L1 with the convex surface facing the object side, and the positive lens element L2. These two lens elements are cemented with each other to constitute a cemented lens element. Thus, a compact lens system is realized. Further, such a construction permits favorable compensation of chromatic aberration.

In the zoom lens systems according to Embodiments III-1 to III-7, in the second lens unit G2, the third lens element L3, which is an object side lens element, has an aspheric surface. Therefore, aberrations, particularly distortion at a wide-angle limit, can be compensated more favorably. Further, in the third lens unit G3, the fifth lens element L5, which is an object side positive lens element, has an aspheric surface. Therefore, aberrations, particularly spherical aberration, can be compensated more favorably.

In the zoom lens systems according to Embodiments III-1 to III-7, the third lens unit G3 is composed of three lens elements, i.e., in order from the object side to the image side, the fifth lens element L5 having positive optical power, the sixth lens element L6 having negative optical power, and the seventh lens element L7 having positive optical power. The fifth lens element L5, which is an object side positive lens element, and the sixth lens element L6 are cemented with each other to constitute a cemented lens element. Therefore, axial aberration, which occurs in the positive lens element, is compensated in the negative lens element, and thus excellent optical performance is achieved with a small number of lens elements.

In the zoom lens systems according to Embodiments III-1 to III-7, the fourth lens unit G4 is composed of a single lens element, and the lens element has positive optical power. Thus, the lens system has a short overall optical length (overall length of lens system). Further, at the time of focusing from an infinite-distance object to a close-distance object, as shown in each Fig., the fourth lens unit G4 is drawn out to the object side so that rapid focusing is achieved easily.

Further, in the zoom lens systems according to Embodiments III-1 to III-7, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1, the second lens unit G2, the third lens unit G3, and the fourth lens unit G4 are moved individually along the optical axis so that zooming is achieved. Then, any lens unit among the first lens unit G1, the second lens unit G2, the third lens unit G3 and the fourth lens unit G4, or alternatively, a sub lens unit consisting of a part of a lens unit is moved in a direction perpendicular to the optical axis, so that image point movement caused by vibration of the entire system is compensated, that is, image blur caused by hand blurring, vibration and the like can be compensated optically.

When image point movement caused by vibration of the entire system is to be compensated, for example, the third lens unit G3 is moved in a direction perpendicular to the optical axis. Thus, image blur is compensated in a state that size increase in the entire zoom lens system is suppressed to realize a compact construction and that excellent imaging characteristics such as small decentering coma aberration and small decentering astigmatism are maintained.

In a case that a lens unit is composed of a plurality of lens elements, the above-mentioned sub lens unit consisting of a part of a lens unit indicates any one lens element or alternatively a plurality of adjacent lens elements among the plurality of lens elements.

The following description is given for conditions preferred to be satisfied by a zoom lens system like the zoom lens systems according to Embodiments I-1 to I-6, II-1 to II-8 and III-1 to III-7. Here, a plurality of preferable conditions are set forth for the zoom lens system according to each embodiment. A construction that satisfies all the plural conditions is most desirable for the zoom lens system. However, when an individual condition is satisfied, a zoom lens system having the corresponding effect is obtained.

In a zoom lens system like the zoom lens systems according to Embodiments I-1 to I-6, in order from the object side to the image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, and the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power (this lens configuration is referred to as basic configuration I of the embodiments, hereinafter), the following conditions (2-2), (b-1) and (a-2) are satisfied.

−2.0<f ₂ /f _(W)<−1.1  (2-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)>30  (a-2)

where,

f₂ is a composite focal length of the second lens unit,

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

The condition (2-2) sets forth a suitable focal length of the second lens unit. When the value exceeds the upper limit of the condition (2-2), the focal length of the second lens unit becomes excessively long, and the amount of movement of the second lens unit increases in zooming, which might result in difficulty in achieving a compact zoom lens system having a zooming ratio exceeding 4.5. On the other hand, when the value goes below the lower limit of the condition (2-2), the focal length of the second lens unit becomes excessively short, which might result in difficulty in compensating variation in aberration caused by movement of the second lens unit.

When at least one of the following conditions (2-2)′ and (2-2)″ is satisfied, the above-mentioned effect is achieved more successfully.

−1.7<f ₂ /f _(W)  (2-2)′

f ₂ /f _(W)<−1.5  (2-2)″

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-6, it is preferable that the following condition (3-2) is satisfied.

1.1<(β_(2T)/β_(2W))/(β_(3T)/β_(3W))<5.2  (3-2)

where,

β_(2T) is a lateral magnification of the second lens unit at a telephoto limit,

β_(2W) is a lateral magnification of the second lens unit at a wide-angle limit,

β_(3T) is a lateral magnification of the third lens unit at a telephoto limit, and

β_(3W) is a lateral magnification of the third lens unit at a wide-angle limit.

The condition (3-2) sets forth the ratio between lateral magnification change in the second lens unit and lateral magnification change in the third lens unit. When the value exceeds the upper limit of the condition (3-2), variable magnification load to the second lens unit becomes excessively great, which might result in difficulty in suppressing occurrence of aberration due to increase in the power, particularly, occurrence of abaxial aberration such as curvature of field at a telephoto limit or magnification chromatic aberration. On the other hand, when the value goes below the lower limit of the condition (3-2), it might be difficult to suppress increase in the size of the lens system due to increase in the amount of movement of the third lens unit, and occurrence of aberration due to increase in the power of the third lens unit, particularly, occurrence of axial aberration such as spherical aberration at a telephoto limit.

When at least one of the following conditions (3-2)′ and (3-2)″ is satisfied, the above-mentioned effect is achieved more successfully.

1.5<(β_(2T)/β_(2W))/(β_(3T)/β_(3W))  (3-2)′

(β_(2T)/β_(2W))/(β_(3T)/β_(3W))<4.5  (3-2)″

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-6, it is preferable that the following condition (4-2) is satisfied.

0.9<M ₁ /M ₃<3.0  (4-2)

where,

M₁ is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive), and

M₃ is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive).

The condition (4-2) sets forth the ratio between the amount of movement of the first lens unit in the direction along the optical axis and the amount of movement of the third lens unit in the direction along the optical axis. When the value exceeds the upper limit of the condition (4-2), the amount of movement of the first lens unit increases and then, the overall optical length increases. As a result, a lens barrel at the time of retraction increases in size, which might result in difficulty in achieving a compact zoom lens system. On the other hand, when the value goes below the lower limit of the condition (4-2), the amount of movement of the third lens unit becomes excessively great, which might result in difficulty in compensating curvature of field or magnification chromatic aberration.

When at least one of the following conditions (4-2)′ and (4-2)″ is satisfied, the above-mentioned effect is achieved more successfully.

1.1<M ₁ /M ₃  (4-2)′

M ₁ /M ₃<2.8  (4-2)″

In a zoom lens system like the zoom lens systems according to Embodiments II-1 to II-8, in order from the object side to the image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, and the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power (this lens configuration is referred to as basic configuration II of the embodiments, hereinafter), the following conditions (3-2), (b-1) and (a-2) are satisfied.

1.1<(β_(2T)/β_(2W))/(β_(3T)/β_(3W))<5.2  (3-2)

f _(T) /f _(W)>6.0  (b-1)

ω_(W)≧30  (a-2)

where,

β_(2T) is a lateral magnification of the second lens unit at a telephoto limit,

β_(2W) is a lateral magnification of the second lens unit at a wide-angle limit,

β_(3T) is a lateral magnification of the third lens unit at a telephoto limit,

β_(3W) is a lateral magnification of the third lens unit at a wide-angle limit,

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

The condition (3-2) sets forth the ratio between lateral magnification change in the second lens unit and lateral magnification change in the third lens unit. When the value exceeds the upper limit of the condition (3-2), variable magnification load to the second lens unit becomes excessively great, which might result in difficulty in suppressing occurrence of aberration due to increase in the power, particularly, occurrence of abaxial aberration such as curvature of field at a telephoto limit or magnification chromatic aberration. On the other hand, when the value goes below the lower limit of the condition (3-2), it might be difficult to suppress increase in the size of the lens system due to increase in the amount of movement of the third lens unit, and occurrence of aberration due to increase in the power of the third lens unit, particularly, occurrence of axial aberration such as spherical aberration at a telephoto limit.

When at least one of the following conditions (3-2)′ and (3-2)″ is satisfied, the above-mentioned effect is achieved more successfully.

1.5<(β_(2T)/β_(2W))/(β_(3T)/β_(3W))  (3-2)′

(β_(2T)/β_(2W))/(β_(3T)/β_(3W))<4.5  (3-2)″

In a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-8, it is preferable that the following condition (2-2) is satisfied.

−2.0<f ₂ /f _(W)<−1.1  (2-2)

where,

f₂ is a composite focal length of the second lens unit, and

f_(W) is a focal length of the entire system at a wide-angle limit.

The condition (2-2) sets forth a suitable focal length of the second lens unit. When the value exceeds the upper limit of the condition (2-2), the focal length of the second lens unit becomes excessively long, and the amount of movement of the second lens unit increases in zooming, which might result in difficulty in achieving a compact zoom lens system having a zooming ratio exceeding 4.5. On the other hand, when the value goes below the lower limit of the condition (2-2), the focal length of the second lens unit becomes excessively short, which might result in difficulty in compensating variation in aberration caused by movement of the second lens unit.

When at least one of the following conditions (2-2)′ and (2-2)″ is satisfied, the above-mentioned effect is achieved more successfully.

−1.7<f ₂ /f _(W)  (2-2)′

f ₂ /f _(W)<−1.5  (2-2)″

In a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-8, it is preferable that the following condition (4-2) is satisfied.

0.9<M ₁ /M ₃<3.0  (4-2)

where,

M₁ is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive), and

M₃ is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive).

The condition (4-2) sets forth the ratio between the amount of movement of the first lens unit in the direction along the optical axis and the amount of movement of the third lens unit in the direction along the optical axis. When the value exceeds the upper limit of the condition (4-2), the amount of movement of the first lens unit increases and then, the overall optical length increases. As a result, a lens barrel at the time of retraction increases in size, which might result in difficulty in achieving a compact zoom lens system. On the other hand, when the value goes below the lower limit of the condition (4-2), the amount of movement of the third lens unit becomes excessively great, which might result in difficulty in compensating curvature of field or magnification chromatic aberration.

When at least one of the following conditions (4-2)′ and (4-2)″ is satisfied, the above-mentioned effect is achieved more successfully.

1.1<M ₁ /M ₃  (4-2)′

M ₁ /M ₃<2.8  (4-2)″

In a zoom lens system like the zoom lens systems according to Embodiments III-1 to III-7, in order from the object side to the image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, and the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power (this lens configuration is referred to as basic configuration III of the embodiments, hereinafter), the following conditions (4-2), (b-1) and (a-2) are satisfied.

0.9<M ₁ /M ₃<3.0  (4-2)

f _(T)/f_(W)>6.0  (b-1)

ω_(W)≧30  (a-2)

where,

M₁ is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),

M₃ is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),

f_(T) is a focal length of the entire system at a telephoto limit,

f_(W) is a focal length of the entire system at a wide-angle limit, and

ω_(W) is a half view angle (°) at a wide-angle limit.

The condition (4-2) sets forth the ratio between the amount of movement of the first lens unit in the direction along the optical axis and the amount of movement of the third lens unit in the direction along the optical axis. When the value exceeds the upper limit of the condition (4-2), the amount of movement of the first lens unit increases and then, the overall optical length increases. As a result, a lens barrel at the time of retraction increases in size, which might result in difficulty in achieving a compact zoom lens system. On the other hand, when the value goes below the lower limit of the condition (4-2), the amount of movement of the third lens unit becomes excessively great, which might result in difficulty in compensating curvature of field or magnification chromatic aberration.

When at least one of the following conditions (4-2)′ and (4-2)″ is satisfied, the above-mentioned effect is achieved more successfully.

1.1<M ₁ /M ₃  (4-2)′

M ₁ /M ₃<2.8  (4-2)″

In a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-7, it is preferable that the following condition (2-2) is satisfied.

−2.0<f ₂ /f _(W)<−1.1  (2-2)

where,

f₂ is a composite focal length of the second lens unit, and

f_(W) is a focal length of the entire system at a wide-angle limit.

The condition (2-2) sets forth a suitable focal length of the second lens unit. When the value exceeds the upper limit of the condition (2-2), the focal length of the second lens unit becomes excessively long, and the amount of movement of the second lens unit increases in zooming, which might result in difficulty in achieving a compact zoom lens system having a zooming ratio exceeding 4.5. On the other hand, when the value goes below the lower limit of the condition (2-2), the focal length of the second lens unit becomes excessively short, which might result in difficulty in compensating variation in aberration caused by movement of the second lens unit.

When at least one of the following conditions (2-2)′ and (2-2)″ is satisfied, the above-mentioned effect is achieved more successfully.

−1.7<f ₂ /f _(W)  (2-2)′

f ₂ /f _(W)<−1.5  (2-2)″

In a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-7, it is preferable that the following condition (3-2) is satisfied.

1.1<(β_(2T)/β_(2W))/(β_(3T)/β_(3W))<5.2  (3-2)

where,

β_(2T) is a lateral magnification of the second lens unit at a telephoto limit,

β_(2W) is a lateral magnification of the second lens unit at a wide-angle limit,

β_(3T) is a lateral magnification of the third lens unit at a telephoto limit, and

β_(3W) is a lateral magnification of the third lens unit at a wide-angle limit.

The condition (3-2) sets forth the ratio between lateral magnification change in the second lens unit and lateral magnification change in the third lens unit. When the value exceeds the upper limit of the condition (3-2), variable magnification load to the second lens unit becomes excessively great, which might result in difficulty in suppressing occurrence of aberration due to increase in the power, particularly, occurrence of abaxial aberration such as curvature of field at a telephoto limit or magnification chromatic aberration. On the other hand, when the value goes below the lower limit of the condition (3-2), it might be difficult to suppress increase in the size of the lens system due to increase in the amount of movement of the third lens unit, and occurrence of aberration due to increase in the power of the third lens unit, particularly, occurrence of axial aberration such as spherical aberration at a telephoto limit.

When at least one of the following conditions (3-2)′ and (3-2)″ is satisfied, the above-mentioned effect is achieved more successfully.

1.5<(β_(2T)/β_(2W))/(β_(3T)/β_(3W))  (3-2)′

(β_(2T)/β_(2W))/(β_(3T)/β_(3W))<4.5  (3-2)″

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-6, in which the second lens unit includes a lens element having positive optical power, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-8, in which the second lens unit includes a lens element having positive optical power, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-7, in which the second lens unit includes a lens element having positive optical power, it is preferable that the following condition (5) is satisfied.

1.88<nd_(2p)<2.20  (5)

where,

nd_(2p) is a refractive index to the d-line of the lens element having positive optical power, which is included in the second lens unit.

The condition (5) sets forth the refractive index of the lens element having positive optical power, which is included in the second lens unit. When the value exceeds the upper limit of the condition (5), it might be difficult to realize mass production of the lens material. On the other hand, when the value goes below the lower limit of the condition (5), it might be difficult to compensate curvature of field and distortion at a wide-angle limit, and coma aberration in the entire zooming range from a wide-angle limit to a telephoto limit.

When at least one of the following conditions (5)′ and (5)″ is satisfied, the above-mentioned effect is achieved more successfully.

1.90<nd_(2p)  (5)′

nd_(2p)<2.15  (5)″

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-6, in which the second lens unit includes a lens element having negative optical power, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-8, in which the second lens unit includes a lens element having negative optical power, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-7, in which the second lens unit includes a lens element having negative optical power, it is preferable that the following condition (6) is satisfied.

0.35<(r _(2na) +r _(2nb))/(r _(2na) −r _(2nb))<1.20  (6)

where,

r_(2na) is a radius of curvature of an object side surface of the lens element having negative optical power, which is included in the second lens unit, and

r_(2nb) is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit.

The condition (6) sets forth the shape factor of the lens element having negative optical power, which is included in the second lens unit. When the value exceeds the upper limit of the condition (6), it might be difficult to compensate curvature of field and distortion at a wide-angle limit. On the other hand, when the value goes below the lower limit of the condition (6), it might be difficult to compensate coma aberration in the entire zooming range from a wide-angle limit to a telephoto limit.

When at least one of the following conditions (6)′ and (6)″ is satisfied, the above-mentioned effect is achieved more successfully.

0.60<(r _(2na) +r _(2nb))/(r _(2na) −r _(2nb))  (6)′

(r _(2na) +r _(2nb))/(r _(2na) −r _(2nb))<0.90  (6)″

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-6, in which the second lens is composed of two lens elements, i.e., in order from the object side to the image side, a lens element having negative optical power and a lens element having positive optical power, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-8, in which the second lens unit is composed of two lens elements, i.e., in order from the object side to the image side, a lens element having negative optical power and a lens element having positive optical power, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-7, in which the second lens unit is composed of two lens elements, i.e., in order from the object side to the image side, a lens element having negative optical power and a lens element having positive optical power, it is preferable that the following condition (7) is satisfied.

−8.5<(r _(2nb) +r _(2pa))/(r _(2nb) −r _(2pa))<−3.5  (7)

where,

r_(2nb) is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit, and

r_(2pa) is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the second lens unit.

The condition (7) sets forth the shape factor of an air lens between the two lens elements constituting the second lens unit. When the value exceeds the upper limit of the condition (7), it might be difficult to compensate curvature of field and distortion at a wide-angle limit. On the other hand, when the value goes below the lower limit of the condition (7), it might be difficult to compensate coma aberration in the entire zooming range from a wide-angle limit to a telephoto limit.

When at least one of the following conditions (7)′ and (7)″ is satisfied, the above-mentioned effect is achieved more successfully.

−8.0<(r _(2nb) +r _(2pa))/(r _(2nb) −r _(2pa))  (7)′

(r _(2nb) +r _(2pa))/(r _(2nb) −r _(2pa))<−5.2  (7)″

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-6, in which the first lens unit includes a lens element having positive optical power, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-8, in which the first lens unit includes a lens element having positive optical power, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-7, in which the first lens unit includes a lens element having positive optical power, it is preferable that the following condition (8) is satisfied.

−1.80<(r _(1pa) +r _(1pb))/(r _(1pa) −r _(1pb))<0.00  (8)

where,

r_(1pa) is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the first lens unit, and

r_(1pb) is a radius of curvature of an image side surface of the lens element having positive optical power, which is included in the first lens unit.

The condition (8) sets forth the shape factor of the lens element having positive optical power, which is included in the first lens unit. When the value exceeds the upper limit of the condition (8), it might be difficult to compensate coma aberration at a telephoto limit. On the other hand, when the value goes below the lower limit of the condition (8), it might be difficult to compensate curvature of field at a wide-angle limit.

When at least one of the following conditions (8)′ and (8)″ is satisfied, the above-mentioned effect is achieved more successfully.

−1.47<(r _(1pa) +r _(1pb))/(r _(1pa) −r _(1pb))  (8)′

(r _(1pa) +r _(1pb))/(r _(1pa) −r _(1pb))<−1.20  (8)″

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-6, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-8, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-7, it is preferable that the following condition (9) is satisfied.

1.87<f ₃ /f _(W)<3.00  (9)

where,

f₃ is a composite focal length of the third lens unit, and

f_(W) is a focal length of the entire system at a wide-angle limit.

The condition (9) sets forth a suitable focal length of the third lens unit. When the value exceeds the upper limit of the condition (9), the focal length of the third lens unit becomes excessively long, which might result in difficulty in achieving a compact zoom lens system. Further, when the value exceeds the upper limit of the condition (9), the amount of movement of, for example, the third lens unit becomes excessively great when the third lens unit is moved in a direction perpendicular to the optical axis for blur compensation. Such a situation is not desirable. On the other hand, when the value goes below the lower limit of the condition (9), the focal length of the third lens unit becomes excessively short. Then, the aberration compensation capability of the third lens unit becomes excessively high, and compensation of various aberrations is not well-balanced, which might result in difficulty in achieving a compact zoom lens system.

When at least one of the following conditions (9)′ and (9)″ is satisfied, the above-mentioned effect is achieved more successfully.

1.90<f ₃ /f _(W)  (9)′

f ₃ /f _(W)<2.06  (9)″

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-6, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-8, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-7, it is preferable that the following condition (10) is satisfied.

0.5<f _(3IL) /f ₃<1.5  (10)

where,

f_(3IL) is a focal length of the image side lens element having positive optical power, which is included in the third lens unit, and

f₃ is a composite focal length of the third lens unit.

The condition (10) sets forth a suitable focal length of the image side lens element having positive optical power, which is included in the third lens unit. When the value exceeds the upper limit of the condition (10), it might be difficult to compensate spherical aberration and coma aberration in a balanced manner by other lens elements, although the overall optical length can be reduced. On the other hand, when the value goes below the lower limit of the condition (10), it might be difficult to reduce the overall optical length, although spherical aberration and coma aberration can be compensated in a balanced manner by other lens elements.

When at least one of the following conditions (10)′ and (10)″ is satisfied, the above-mentioned effect is achieved more successfully.

1.0<f _(3IL) /f ₃  (10)′

f _(3IL) /f ₃<1.3  (10)″

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-6, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-8, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-7, it is preferable that the following condition (11) is satisfied.

−1.00<f _(3n) /f ₃<−0.25  (11)

where,

f_(3n) is a focal length of the lens element having negative optical power, which is included in the third lens unit, and

f₃ is a composite focal length of the third lens unit.

The condition (11) sets forth a suitable focal length of the lens element having negative optical power, which is included in the third lens unit. When the value exceeds the upper limit of the condition (11), it might be difficult to compensate spherical aberration and coma aberration in a balanced manner by other lens elements, although the overall optical length can be reduced. On the other hand, when the value goes below the lower limit of the condition (11), it might be difficult to reduce the overall optical length, although spherical aberration and coma aberration can be compensated in a balanced manner by other lens elements.

When at least one of the following conditions (11)′ and (11)″ is satisfied, the above-mentioned effect is achieved more successfully.

−0.68<f _(3n) /f ₃  (11)′

f _(3n) /f ₃<−0.46  (11)″

Each of the lens units constituting the zoom lens system according to any of Embodiments I-1 to I-6, II-1 to II-8 and III-1 to III-7 is composed exclusively of refractive type lens elements that deflect the incident light by refraction (that is, lens elements of a type in which deflection is achieved at the interface between media each having a distinct refractive index). However, the present invention is not limited to this. For example, the lens units may employ diffractive type lens elements that deflect the incident light by diffraction; refractive-diffractive hybrid type lens elements that deflect the incident light by a combination of diffraction and refraction; or gradient index type lens elements that deflect the incident light by distribution of refractive index in the medium. In particular, in the refractive-diffractive hybrid type lens elements, when a diffraction structure is formed in the interface between media having mutually different refractive indices, wavelength dependence in the diffraction efficiency is improved. Thus, such a configuration is preferable.

Moreover, in each embodiment, a configuration has been described that on the object side relative to the image surface S (that is, between the image surface S and the most image side lens surface of the fourth lens unit G4), a plane parallel plate P such as an optical low-pass filter and a face plate of an image sensor is provided. This low-pass filter may be: a birefringent type low-pass filter made of, for example, a crystal whose predetermined crystal orientation is adjusted; or a phase type low-pass filter that achieves required characteristics of optical cut-off frequency by diffraction.

Embodiment I-7

FIG. 15 is a schematic construction diagram of a digital still camera according to Embodiment I-7. In FIG. 15, the digital still camera comprises: an imaging device having a zoom lens system 1 and an image sensor 2 composed of a CCD; a liquid crystal display monitor 3; and a body 4. The employed zoom lens system 1 is a zoom lens system according to Embodiment I-1. In FIG. 15, the zoom lens system 1 comprises a first lens unit G1, a second lens unit G2, an aperture diaphragm A, a third lens unit G3, and a fourth lens unit G4. In the body 4, the zoom lens system 1 is arranged on the front side, and the image sensor 2 is arranged on the rear side of the zoom lens system 1. On the rear side of the body 4, the liquid crystal display monitor 3 is arranged, and an optical image of a photographic object generated by the zoom lens system 1 is formed on an image surface S.

A lens barrel comprises a main barrel 5, a moving barrel 6 and a cylindrical cam 7. When the cylindrical cam 7 is rotated, the first lens unit G1, the second lens unit G2, the aperture diaphragm A and the third lens unit G3, and the fourth lens unit G4 move to predetermined positions relative to the image sensor 2, so that zooming from a wide-angle limit to a telephoto limit is achieved. The fourth lens unit G4 is movable in an optical axis direction by a motor for focus adjustment.

In this way, when the zoom lens system according to Embodiment I-1 is employed in a digital still camera, a small digital still camera is obtained that has a high resolution and high capability of compensating the curvature of field and that has a short overall length of lens system at the time of non-use. Here, in the digital still camera shown in FIG. 15, any one of the zoom lens systems according to Embodiments I-2 to I-6 may be employed in place of the zoom lens system according to Embodiment I-1. Further, the optical system of the digital still camera shown in FIG. 15 is applicable also to a digital video camera for moving images. In this case, moving images with high resolution can be acquired in addition to still images.

Here, the digital still camera according to Embodiment I-7 has been described for a case that the employed zoom lens system 1 is a zoom lens system according to any of Embodiments I-1 to I-6. However, in these zoom lens systems, the entire zooming range need not be used. That is, in accordance with a desired zooming range, a range where satisfactory optical performance is obtained may exclusively be used. Then, the zoom lens system may be used as one having a lower magnification than the zoom lens systems described in Embodiments I-1 to I-6.

Further, Embodiment I-7 has been described for a case that the zoom lens system is applied to a lens barrel of so-called barrel retraction construction. However, the present invention is not limited to this. For example, the zoom lens system may be applied to a lens barrel of so-called bending construction where a prism having an internal reflective surface or a front surface reflective minor is arranged at an arbitrary position within the first lens unit G1 or the like. Further, in Embodiment I-7, the zoom lens system may be applied to a so-called sliding lens barrel in which a part of the lens units constituting the zoom lens system like the entirety of the second lens unit G2, the entirety of the third lens unit G3, or alternatively a part of the second lens unit G2 or the third lens unit G3 is caused to escape from the optical axis at the time of retraction.

Further, an imaging device comprising a zoom lens system according to any of Embodiments I-1 to I-6 described above and an image sensor such as a CCD or a CMOS may be applied to a mobile telephone, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a Web camera, a vehicle-mounted camera or the like.

Embodiment II-9

FIG. 36 is a schematic construction diagram of a digital still camera according to Embodiment II-9. In FIG. 36, the digital still camera comprises: an imaging device having a zoom lens system 1 and an image sensor 2 composed of a CCD; a liquid crystal display monitor 3; and a body 4. The employed zoom lens system 1 is a zoom lens system according to Embodiment II-1. In FIG. 36, the zoom lens system 1 comprises a first lens unit G1, a second lens unit G2, an aperture diaphragm A, a third lens unit G3, and a fourth lens unit G4. In the body 4, the zoom lens system 1 is arranged on the front side, and the image sensor 2 is arranged on the rear side of the zoom lens system 1. On the rear side of the body 4, the liquid crystal display monitor 3 is arranged, and an optical image of a photographic object generated by the zoom lens system 1 is formed on an image surface S.

A lens barrel comprises a main barrel 5, a moving barrel 6 and a cylindrical cam 7. When the cylindrical cam 7 is rotated, the first lens unit G1, the second lens unit G2, the aperture diaphragm A and the third lens unit G3, and the fourth lens unit G4 move to predetermined positions relative to the image sensor 2, so that zooming from a wide-angle limit to a telephoto limit is achieved. The fourth lens unit G4 is movable in an optical axis direction by a motor for focus adjustment.

In this way, when the zoom lens system according to Embodiment II-1 is employed in a digital still camera, a small digital still camera is obtained that has a high resolution and high capability of compensating the curvature of field and that has a short overall length of lens system at the time of non-use. Here, in the digital still camera shown in FIG. 36, any one of the zoom lens systems according to Embodiments II-2 to II-8 may be employed in place of the zoom lens system according to Embodiment II-1. Further, the optical system of the digital still camera shown in FIG. 36 is applicable also to a digital video camera for moving images. In this case, moving images with high resolution can be acquired in addition to still images.

Here, the digital still camera according to Embodiment II-9 has been described for a case that the employed zoom lens system 1 is a zoom lens system according to any of Embodiments II-1 to II-8. However, in these zoom lens systems, the entire zooming range need not be used. That is, in accordance with a desired zooming range, a range where satisfactory optical performance is obtained may exclusively be used. Then, the zoom lens system may be used as one having a lower magnification than the zoom lens systems described in Embodiments II-1 to II-8.

Further, Embodiment II-9 has been described for a case that the zoom lens system is applied to a lens barrel of so-called barrel retraction construction. However, the present invention is not limited to this. For example, the zoom lens system may be applied to a lens barrel of so-called bending construction where a prism having an internal reflective surface or a front surface reflective minor is arranged at an arbitrary position within the first lens unit G1 or the like. Further, in Embodiment II-9, the zoom lens system may be applied to a so-called sliding lens barrel in which a part of the lens units constituting the zoom lens system like the entirety of the second lens unit G2, the entirety of the third lens unit G3, or alternatively a part of the second lens unit G2 or the third lens unit G3 is caused to escape from the optical axis at the time of retraction.

Further, an imaging device comprising a zoom lens system according to any of Embodiments II-1 to II-8 described above and an image sensor such as a CCD or a CMOS may be applied to a mobile telephone, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a Web camera, a vehicle-mounted camera or the like.

Embodiment III-8

FIG. 55 is a schematic construction diagram of a digital still camera according to Embodiment III-8. In FIG. 55, the digital still camera comprises: an imaging device having a zoom lens system 1 and an image sensor 2 composed of a CCD; a liquid crystal display monitor 3; and a body 4. The employed zoom lens system 1 is a zoom lens system according to Embodiment III-1. In FIG. 55, the zoom lens system 1 comprises a first lens unit G1, a second lens unit G2, an aperture diaphragm A, a third lens unit G3, and a fourth lens unit G4. In the body 4, the zoom lens system 1 is arranged on the front side, and the image sensor 2 is arranged on the rear side of the zoom lens system 1. On the rear side of the body 4, the liquid crystal display monitor 3 is arranged, and an optical image of a photographic object generated by the zoom lens system 1 is formed on an image surface S.

A lens barrel comprises a main barrel 5, a moving barrel 6 and a cylindrical cam 7. When the cylindrical cam 7 is rotated, the first lens unit G1, the second lens unit G2, the aperture diaphragm A and the third lens unit G3, and the fourth lens unit G4 move to predetermined positions relative to the image sensor 2, so that zooming from a wide-angle limit to a telephoto limit is achieved. The fourth lens unit G4 is movable in an optical axis direction by a motor for focus adjustment.

In this way, when the zoom lens system according to Embodiment III-1 is employed in a digital still camera, a small digital still camera is obtained that has a high resolution and high capability of compensating the curvature of field and that has a short overall length of lens system at the time of non-use. Here, in the digital still camera shown in FIG. 55, any one of the zoom lens systems according to Embodiments III-2 to III-7 may be employed in place of the zoom lens system according to Embodiment III-1. Further, the optical system of the digital still camera shown in FIG. 55 is applicable also to a digital video camera for moving images. In this case, moving images with high resolution can be acquired in addition to still images.

Here, the digital still camera according to Embodiment III-8 has been described for a case that the employed zoom lens system 1 is a zoom lens system according to any of Embodiments III-1 to III-7. However, in these zoom lens systems, the entire zooming range need not be used. That is, in accordance with a desired zooming range, a range where satisfactory optical performance is obtained may exclusively be used. Then, the zoom lens system may be used as one having a lower magnification than the zoom lens systems described in Embodiments III-1 to III-7.

Further, Embodiment III-8 has been described for a case that the zoom lens system is applied to a lens barrel of so-called barrel retraction construction. However, the present invention is not limited to this. For example, the zoom lens system may be applied to a lens barrel of so-called bending construction where a prism having an internal reflective surface or a front surface reflective minor is arranged at an arbitrary position within the first lens unit G1 or the like. Further, in Embodiment III-8, the zoom lens system may be applied to a so-called sliding lens barrel in which a part of the lens units constituting the zoom lens system like the entirety of the second lens unit G2, the entirety of the third lens unit G3, or alternatively a part of the second lens unit G2 or the third lens unit G3 is caused to escape from the optical axis at the time of retraction.

Further, an imaging device comprising a zoom lens system according to any of Embodiments III-1 to III-7 described above and an image sensor such as a CCD or a CMOS may be applied to a mobile telephone, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a Web camera, a vehicle-mounted camera or the like.

Numerical examples are described below in which the zoom lens systems according to Embodiments I-1 to I-6, II-1 to II-8 and III-1 to III-7 are implemented. Here, in the numerical examples, the units of length are all “mm”, while the units of view angle are all “°”. Moreover, in the numerical examples, r is the radius of curvature, d is the axial distance, nd is the refractive index to the d-line, and vd is the Abbe number to the d-line. In the numerical examples, the surfaces marked with * are aspherical surfaces, and the aspherical surface configuration is defined by the following expression.

$Z = {\frac{h^{2}/r}{1 + \sqrt{1 - {\left( {1 + \kappa} \right)\left( {h/r} \right)^{2}}}} + {A\; 4h^{4}} + {A\; 6\; h^{6}} + {A\; 8\; h^{8}} + {A\; 10\; h^{10}}}$

Here, κ is the conic constant, A4, A6, A8 and A10 are a fourth-order, sixth-order, eighth-order and tenth-order aspherical coefficients, respectively.

FIGS. 2, 5, 7, 10, 12 and 14 are longitudinal aberration diagrams of the zoom lens systems according to Embodiments I-1 to I-6, respectively.

FIGS. 17, 19, 22, 25, 28, 31, 33 and 35 are longitudinal aberration diagrams of the zoom lens systems according to Embodiments II-1 to II-8, respectively.

FIGS. 38, 40, 43, 46, 49, 52 and 54 are longitudinal aberration diagrams of the zoom lens systems according to Embodiments III-1 to III-7, respectively.

In each longitudinal aberration diagram, part (a) shows the aberration at a wide-angle limit, part (b) shows the aberration at a middle position, and part (c) shows the aberration at a telephoto limit. Each longitudinal aberration diagram, in order from the left-hand side, shows the spherical aberration (SA (mm)), the astigmatism (AST (mm)) and the distortion (DIS (%)). In each spherical aberration diagram, the vertical axis indicates the F-number (in each Fig., indicated as F), and the solid line, the short dash line and the long dash line indicate the characteristics to the d-line, the F-line and the C-line, respectively. In each astigmatism diagram, the vertical axis indicates the image height (in each Fig., indicated as H), and the solid line and the dash line indicate the characteristics to the sagittal plane (in each Fig., indicated as “s”) and the meridional plane (in each Fig., indicated as “m”), respectively. In each distortion diagram, the vertical axis indicates the image height (in each Fig., indicated as H).

FIGS. 3 and 8 are lateral aberration diagrams of the zoom lens systems at a telephoto limit according to Embodiments I-1 and I-3, respectively.

FIGS. 20, 23, 26 and 29 are lateral aberration diagrams of the zoom lens systems at a telephoto limit according to Embodiments II-2, II-3, II-4 and II-5, respectively.

FIGS. 41, 44, 47 and 50 are lateral aberration diagrams of the zoom lens systems at a telephoto limit according to Embodiments III-2, III-3, III-4 and III-5, respectively.

In each lateral aberration diagram, the aberration diagrams in the upper three parts correspond to a basic state where image blur compensation is not performed at a telephoto limit, while the aberration diagrams in the lower three parts correspond to an image blur compensation state where the entirety of the third lens unit G3 is moved by a predetermined amount in a direction perpendicular to the optical axis at a telephoto limit. Among the lateral aberration diagrams of a basic state, the upper part shows the lateral aberration at an image point of 70% of the maximum image height, the middle part shows the lateral aberration at the axial image point, and the lower part shows the lateral aberration at an image point of −70% of the maximum image height. Among the lateral aberration diagrams of an image blur compensation state, the upper part shows the lateral aberration at an image point of 70% of the maximum image height, the middle part shows the lateral aberration at the axial image point, and the lower part shows the lateral aberration at an image point of −70% of the maximum image height. In each lateral aberration diagram, the horizontal axis indicates the distance from the principal ray on the pupil surface, and the solid line, the short dash line and the long dash line indicate the characteristics to the d-line, the F-line and the C-line, respectively. In each lateral aberration diagram, the meridional plane is adopted as the plane containing the optical axis of the first lens unit G1 and the optical axis of the third lens unit G3.

Here, in the zoom lens system according to each example, the amount of movement of the third lens unit G3 in a direction perpendicular to the optical axis in the image blur compensation state at a telephoto limit is as follows.

Amount of movement Example (mm) I-1 0.122 I-3 0.162 II-2 0.122 II-3 0.129 II-4 0.164 II-5 0.162 III-2 0.129 III-3 0.132 III-4 0.164 III-5 0.162

Here, when the shooting distance is infinity, at a telephoto limit, the amount of image decentering in a case that the zoom lens system inclines by 0.3° is equal to the amount of image decentering in a case that the entirety of the third lens unit G3 displaces in parallel by each of the above-mentioned values in a direction perpendicular to the optical axis.

As seen from the lateral aberration diagrams, satisfactory symmetry is obtained in the lateral aberration at the axial image point. Further, when the lateral aberration at the +70% image point and the lateral aberration at the −70% image point are compared with each other in the basic state, all have a small degree of curvature and almost the same inclination in the aberration curve. Thus, decentering coma aberration and decentering astigmatism are small. This indicates that sufficient imaging performance is obtained even in the image blur compensation state. Further, when the image blur compensation angle of a zoom lens system is the same, the amount of parallel translation required for image blur compensation decreases with decreasing focal length of the entire zoom lens system. Thus, at arbitrary zoom positions, sufficient image blur compensation can be performed for image blur compensation angles up to 0.3° without degrading the imaging characteristics.

Numerical Example I-1

The zoom lens system of Numerical Example I-1 corresponds to Embodiment I-1 shown in FIG. 1. Table I-1 shows the surface data of the zoom lens system of Numerical Example I-1. Table I-2 shows the aspherical data. Table I-3 shows various data.

TABLE I-1 (Surface data) Surface number r d nd vd Object surface ∞ 1 22.20034 0.80000 1.92286 20.9 2 16.29755 3.20000 1.72916 54.7 3 139.18600 Variable  4* −59.14503 1.10000 1.85976 40.6  5* 5.94383 1.39250 6 8.10158 1.70000 1.94595 18.0 7 14.57504 Variable 8(Diaphragm) ∞ 0.00000  9* 4.39479 2.50000 1.85135 40.1 10 9.90230 0.40000 1.92286 20.9 11 3.68214 0.50000 12 10.58272 1.50000 1.77250 49.6 13 −59.81446 Variable  14* 14.64296 1.80000 1.62299 58.1 15 −81.51573 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE I-2 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 1.61461E−04, A6 = −3.32899E−06, A8 = 4.44142E−08 A10 = −2.25656E−10 Surface No. 5 K = −2.51025E+00, A4 = 1.41935E−03, A6 = −1.36992E−05, A8 = 1.83402E−07 A10 = 1.40309E−09 Surface No. 9 K = −4.30638E−01, A4 = 1.17618E−04, A6 = 2.71101E−05, A8 = −5.66873E−06 A10 = 6.02589E−07 Surface No. 14 K = 0.00000E+00, A4 = 5.90546E−05, A6 = 6.41505E−06, A8 = −3.18335E−07 A10 = 6.30964E−09

TABLE I-3 (Various data) Zooming ratio 6.54203 Wide-angle limit Middle position Telephoto limit Focal length 6.1188 12.9779 40.0295 F-number 3.23953 3.96695 5.67089 View angle 34.8313 16.7900 5.3897 Image height 3.8300 3.8300 3.8300 Overall length of lens system 41.5545 37.1082 52.5801 BF 0.50591 0.51794 0.52121 d3 0.6000 4.2068 17.3105 d7 16.5610 4.8693 1.0000  d13 2.3036 3.1689 16.2175  d15 5.6914 8.4528 1.6384 Entrance pupil position 13.4247 15.7784 54.0064 Exit pupil position −14.4333 −18.8833 −435.0709 Front principal points position 17.0374 20.0751 90.3573 Back principal points position 35.4356 24.1303 12.5506 Single lens data Lens element Initial surface number Focal length 1 1 −71.0393 2 2 25.0404 3 4 −6.2333 4 6 17.1001 5 9 7.6785 6 10 −6.5541 7 12 11.7490 8 14 20.0692 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 39.94948 4.00000 −0.67384 1.09928 2 4 −10.25874 4.19250 0.24741 1.66395 3 8 12.13874 4.90000 −2.11245 0.31040 4 14 20.06917 1.80000 0.17011 0.85302 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.39544 −0.45929 −1.11120 3 8 −0.63375 −1.49544 −1.11002 4 14 0.61117 0.47297 0.81236

Numerical Example I-2

The zoom lens system of Numerical Example I-2 corresponds to Embodiment I-2 shown in FIG. 4. Table I-4 shows the surface data of the zoom lens system of Numerical Example I-2. Table I-5 shows the aspherical data. Table I-6 shows various data.

TABLE I-4 (Surface data) Surface number r d nd vd Object surface ∞  1 22.98440 0.80000 2.00170 20.6  2 17.06934 3.00000 1.80420 46.5  3 88.78142 Variable  4* −221.40520 1.00000 1.85976 40.6  5* 5.56527 1.39220  6 8.04492 1.70000 2.00170 20.6  7 14.35270 Variable  8(Diaphragm) ∞ 0.00000  9* 4.58023 2.50000 1.77377 47.2 10 13.17091 0.40000 1.84666 23.8 11 3.98157 0.50000 12 11.32115 1.50000 1.80420 46.5 13 −172.13620 Variable 14* 15.84590 1.80000 1.80420 46.5 15 696.20750 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE I-5 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = −7.92798E−05, A6 = 1.31994E−06, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 5 K = −1.64472E+00, A4 = 8.04967E−04, A6 = −4.09967E−06, A8 = 9.96207E−08 A10 = 3.79729E−09 Surface No. 9 K = −3.85474E−01, A4 = 7.27041E−05, A6 = 1.43854E−05, A8 = −3.37492E−06 A10 = 3.29500E−07 Surface No. 14 K = 0.00000E+00, A4 = 4.52987E−05, A6 = 3.58657E−07, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE I-6 (Various data) Zooming ratio 6.54358 Wide-angle Middle Telephoto limit position limit Focal length 6.7963 17.3331 44.4720 F-number 3.43627 3.88419 5.87738 View angle 32.0601 12.5864 4.8709 Image height 3.8300 3.8300 3.8300 Overall length 44.4426 45.4138 57.7571 of lens system BF 0.49855 0.53779 0.50695 d3 0.5000 11.3199 18.7857 d7 17.5535 5.3040 1.4500 d13 3.9343 3.8667 18.8854 d15 6.3640 8.7933 2.5369 Entrance pupil 13.4475 33.8815 59.9670 position Exit pupil −18.1536 −20.4311 278.7394 position Front principal 17.7674 36.8869 111.5473 points position Back principal 37.6463 28.0807 13.2851 points position Single lens data Lens Initial surface Focal element number length 1 1 −71.0212 2 2 25.7964 3 4 −6.3015 4 6 16.1025 5 9 8.0531 6 10 −6.8775 7 12 13.2571 8 14 20.1391 Zoom lens unit data Front Back Initial Overall principal principal Lens surface Focal length of points points unit No. length lens unit position position 1 1 42.02118 3.80000 −0.98229 0.81730 2 4 −10.85227 4.09220 0.21956 1.61285 3 8 13.70595 4.90000 −2.18526 0.19508 4 14 20.13910 1.80000 −0.02321 0.78029 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.39511 −0.65191 −1.18204 3 8 −0.71083 −1.39583 −1.16962 4 14 0.57587 0.45330 0.76549

Numerical Example I-3

The zoom lens system of Numerical Example I-3 corresponds to Embodiment I-3 shown in FIG. 6. Table I-7 shows the surface data of the zoom lens system of Numerical Example I-3. Table I-8 shows the aspherical data. Table I-9 shows various data.

TABLE I-7 (Surface data) Surface number r d nd vd Object surface ∞  1 21.11164 0.80000 2.00170 20.6  2 15.12358 2.50000 1.80420 46.5  3* 88.24478 Variable  4* −69.21321 1.00000 1.85976 40.6  5* 4.93236 1.09570  6 7.22589 1.70000 2.00170 20.6  7 14.35270 Variable  8(Diaphragm) ∞ 0.00000  9* 4.94313 2.10000 1.77377 47.2 10 10.82877 0.80000 1.92286 20.9 11 4.47121 0.50000 12 11.90782 1.50000 1.80420 46.5 13 −39.79054 Variable 14* 20.42889 1.80000 1.80420 46.5 15 −248.53400 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE I-8 (Aspherical data) Surface No. 3 K = 0.00000E+00, A4 = 2.27928E−06, A6 = 3.00081E−10, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 4 K = 0.00000E+00, A4 = 5.20294E−05, A6 = −4.16769E−08, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 5 K = −2.47053E+00, A4 = 2.06679E−03, A6 = −2.74077E−05, A8 = 6.95651E−07 A10 = −4.23395E−09 Surface No. 9 K = −4.61701E−01, A4 = 8.60229E−05, A6 = 2.31646E−05, A8 = −4.52966E−06 A10 = 4.13883E−07 Surface No. 14 K = 0.00000E+00, A4 = 2.57276E−05, A6 = 3.06354E−06, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE I-9 (Various data) Zooming ratio 6.54191 Wide-angle Middle Telephoto limit position limit Focal length 6.7983 17.3294 44.4739 F-number 3.40234 3.91077 4.59471 View angle 32.0530 12.6173 4.9207 Image height 3.8300 3.8300 3.8300 Overall length 40.8782 44.9165 53.2755 of lens system BF 0.50271 0.52741 0.50364 d3 0.6000 11.2009 20.8199 d7 14.7539 5.4351 1.4500 d13 2.5571 3.2145 13.2000 d15 7.6688 9.7429 2.5063 Entrance pupil 11.7579 33.9417 82.6375 position Exit pupil −16.5435 −19.7880 −56.1280 position Front principal 15.8449 36.4888 92.1852 points position Back principal 34.0799 27.5871 8.8016 points position Single lens data Lens Initial surface Focal element number length 1 1 −57.0431 2 2 22.3546 3 4 −5.3221 4 6 12.9783 5 9 10.1707 6 10 −8.7828 7 12 11.5458 8 14 23.5435 Zoom lens unit data Front Back Initial Overall principal principal Lens surface Focal length of points points unit No. length lens unit position position 1 1 38.26554 3.30000 −0.82482 0.73786 2 4 −9.46936 3.79570 0.23471 1.62366 3 8 12.87340 4.90000 −1.23135 0.84238 4 14 23.54354 1.80000 0.07600 0.87535 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.37282 −0.63989 −1.82826 3 8 −0.81370 −1.42546 −0.78982 4 14 0.58564 0.49650 0.80488

Numerical Example I-4

The zoom lens system of Numerical Example I-4 corresponds to Embodiment I-4 shown in FIG. 9. Table I-10 shows the surface data of the zoom lens system of Numerical Example I-4. Table I-11 shows the aspherical data. Table I-12 shows various data.

TABLE I-10 (Surface data) Surface number r d nd vd Object surface ∞  1 22.01411 0.80000 2.14422 17.5  2 16.76615 2.50000 1.82080 42.7  3* 101.42760 Variable  4* −71.58793 1.00000 1.85976 40.6  5* 5.13092 1.09570  6 7.40182 1.70000 2.00170 20.6  7 14.35270 Variable  8(Diaphragm) ∞ 0.00000  9* 4.80218 2.10000 1.77377 47.2 10 9.87535 0.80000 1.92286 20.9 11 4.30138 0.50000 12 11.64846 1.50000 1.80420 46.5 13 −48.27259 Variable 14* 19.51788 1.30000 1.80420 46.5 15 −601.21670 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE I-11 (Aspherical data) Surface No. 3 K = 0.00000E+00, A4 = 1.96399E−06, A6 = 8.38790E−10, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 4 K = 0.00000E+00, A4 = 2.08635E−05, A6 = 4.82445E−07, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 5 K = −2.72794E+00, A4 = 2.05037E−03, A6 = −3.37206E−05, A8 = 8.72404E−07 A10 = −5.23638E−09 Surface No. 9 K = −4.61942E−01, A4 = 1.03075E−04, A6 = 2.43831E−05, A8 = −4.51015E−06 A10 = 4.15499E−07 Surface No. 14 K = 0.00000E+00, A4 = 2.82102E−05, A6 = 3.05454E−06, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE I-12 (Various data) Zooming ratio 6.54969 Wide-angle Middle Telephoto limit position limit Focal length 6.7999 17.3217 44.5372 F-number 3.42679 4.00985 4.56886 View angle 32.0408 12.5843 4.9066 Image height 3.8300 3.8300 3.8300 Overall length 41.1512 44.8950 53.2882 of lens system BF 0.50957 0.51183 0.52021 d3 0.6000 10.9391 21.3625 d7 15.4165 5.6233 1.3000 d13 2.4448 3.4802 12.6158 d15 7.8846 10.0448 3.1939 Entrance pupil 11.9887 32.6384 82.8481 position Exit pupil −16.1869 −20.1889 −50.2594 position Front principal 16.0192 35.4659 88.3232 points position Back principal 34.3513 27.5733 8.7510 points position Single lens data Lens Initial surface Focal element number length 1 1 −66.9089 2 2 24.1504 3 4 −5.5354 4 6 13.5941 5 9 10.2331 6 10 −8.8686 7 12 11.8005 8 14 23.5288 Zoom lens unit data Front Back Initial Overall principal principal Lens surface Focal length of points points unit No. length lens unit position position 1 1 39.22731 3.30000 −0.83975 0.75865 2 4 −9.73077 3.79570 0.26561 1.66074 3 8 13.01946 4.90000 −1.48970 0.66880 4 14 23.52878 1.30000 0.02268 0.60146 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.37298 −0.61781 −1.82667 3 8 −0.79375 −1.44795 −0.79235 4 14 0.58553 0.49362 0.78444

Numerical Example I-5

The zoom lens system of Numerical Example I-5 corresponds to Embodiment I-5 shown in FIG. 11. Table I-13 shows the surface data of the zoom lens system of Numerical Example I-5. Table I-14 shows the aspherical data. Table I-15 shows various data.

TABLE I-13 (Surface data) Surface number r d nd vd Object surface ∞  1 25.31776 0.80000 1.92286 20.9  2 18.23858 2.90000 1.77250 49.6  3 141.43600 Variable  4* −74.12426 0.95000 1.85976 40.6  5* 5.92627 1.47140  6 8.28920 1.70000 2.14422 17.5  7 12.83109 Variable  8(Diaphragm) ∞ 0.00000  9* 4.63999 2.45000 1.80139 45.4 10 11.40598 0.50000 1.92286 20.9 11 4.08736 0.48000 12 11.58038 1.50000 1.80420 46.5 13 −46.42335 Variable 14* 16.70893 1.70000 1.80610 40.7 15 −271.10350 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE I-14 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 8.00930E−05, A6 = −8.24171E−07, A8 = 7.02480E−09 A10 = 0.00000E+00 Surface No. 5 K = −2.80748E+00, A4 = 1.51170E−03, A6 = −1.93182E−05, A8 = 3.79463E−07 A10 = −1.27953E−09 Surface No. 9 K = −3.81122E−01, A4 = 1.92672E−05, A6 = 2.36355E−05, A8 = −5.76293E−06 A10 = 5.76364E−07 Surface No. 14 K = 0.00000E+00, A4 = 5.48957E−05, A6 = 4.00480E−07, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE I-15 (Various data) Zooming ratio 6.54099 Wide-angle Middle Telephoto limit position limit Focal length 6.1338 15.6371 40.1213 F-number 3.35969 3.84965 5.84335 View angle 35.0631 13.8718 5.4025 Image height 3.8300 3.8300 3.8300 Overall length 43.0188 45.0018 57.0268 of lens system BF 0.49471 0.53782 0.50457 d3 0.5000 11.4355 18.9917 d7 17.0651 5.3765 1.4500 d13 3.8959 4.3424 17.9582 d15 5.6117 7.8582 2.6709 Entrance pupil 12.7522 32.7502 57.3438 position Exit pupil −17.6154 −20.9508 309.8164 position Front principal 16.8085 37.0083 102.6693 points position Back principal 36.8850 29.3648 16.9055 points position Single lens data Lens Initial surface Focal element number length 1 1 −74.7335 2 2 26.8298 3 4 −6.3478 4 6 17.0587 5 9 8.4064 6 10 −7.1366 7 12 11.6594 8 14 19.5762 Zoom lens unit data Front Back Initial Overall principal principal Lens surface Focal length of points points unit No. length lens unit position position 1 1 43.09186 3.70000 −0.63212 1.04900 2 4 −10.40411 4.12140 0.28566 1.75797 3 8 12.61365 4.93000 −1.72530 0.54757 4 14 19.57623 1.70000 0.05479 0.81105 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.35568 −0.56805 −0.96698 3 8 −0.65716 −1.29835 −1.26908 4 14 0.60898 0.49202 0.75870

Numerical Example I-6

The zoom lens system of Numerical Example I-6 corresponds to Embodiment I-6 shown in FIG. 13. Table I-16 shows the surface data of the zoom lens system of Numerical Example I-6. Table I-17 shows the aspherical data. Table I-18 shows various data.

TABLE I-16 (Surface data) Surface number r d nd vd Object surface ∞  1 25.31390 0.80000 1.92286 20.9  2 18.37307 2.90000 1.77250 49.6  3 127.09120 Variable  4* −72.33967 0.95000 1.85976 40.6  5* 5.53361 1.50880  6 8.10144 1.70000 2.14422 17.5  7 12.83109 Variable  8(Diaphragm) ∞ 0.00000  9* 4.58126 2.45000 1.80139 45.4 10 12.89458 0.50000 1.92286 20.9 11 4.09435 0.48000 12 12.11282 1.50000 1.80420 46.5 13 −29.99816 Variable 14* 16.30826 1.70000 1.82080 42.7 15 −204.49060 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE I-17 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 1.38654E−04, A6 = −2.03482E−06, A8 = 1.30075E−08 A10 = 0.00000E+00 Surface No. 5 K = −2.38369E+00, A4 = 1.55078E−03, A6 = −1.46113E−05, A8 = 2.67367E−07 A10 = −2.02236E−09 Surface No. 9 K = −4.10236E−01, A4 = 2.02270E−05, A6 = 2.52654E−05, A8 = −7.12069E−06 A10 = 8.11753E−07 Surface No. 14 K = 0.00000E+00, A4 = 5.64788E−05, A6 = 4.75905E−07, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE I-18 (Various data) Zooming ratio 6.54149 Wide-angle Middle Telephoto limit position limit Focal length 5.5377 14.1127 36.2248 F-number 3.29490 3.84420 5.79699 View angle 37.8649 15.3659 5.9868 Image height 3.8300 3.8300 3.8300 Overall length 41.5403 44.0499 56.5476 of lens system BF 0.51202 0.52769 0.52473 d3 0.5000 11.0956 19.1926 d7 16.2704 5.0362 1.4500 d13 3.8899 4.8390 17.2154 d15 4.8791 7.0627 2.6761 Entrance pupil 12.0360 30.5678 56.7404 position Exit pupil −17.3975 −22.2119 209.0752 position Front principal 15.8615 35.9218 99.2574 points position Back principal 36.0026 29.9372 20.3228 points position Single lens data Lens Initial surface Focal element number length 1 1 −76.8613 2 2 27.4838 3 4 −5.9453 4 6 16.1170 5 9 7.8392 6 10 −6.6830 7 12 10.9026 8 14 18.4654 Zoom lens unit data Front Back Initial Overall principal principal Lens surface Focal length of points points unit No. length lens unit position position 1 1 44.06577 3.70000 −0.70119 0.98430 2 4 −9.81147 4.15880 0.22506 1.68504 3 8 11.74129 4.93000 −1.33477 0.80049 4 14 18.46535 1.70000 0.06920 0.83229 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.31841 −0.48529 −0.80946 3 8 −0.63113 −1.30361 −1.36507 4 14 0.62535 0.50625 0.74396

The following Table I-19 shows the corresponding values to the individual conditions in the zoom lens systems of each of Numerical Examples.

TABLE I-19 (Values corresponding to conditions) Example Condition I-1 I-2 I-3 I-4 I-5 I-6 (2-2) f₂/f_(W) −1.68 −1.60 −1.39 −1.43 −1.70 −1.77 (b-1) f_(T)/f_(W) 6.54 6.54 6.54 6.55 6.54 6.54 (a-2) ω_(W) 34.84 32.06 32.06 32.05 35.06 37.88 (3-2) (β_(2T)/β_(2W))/(β_(3T)/β_(3W)) 1.60 1.82 5.05 4.91 1.41 1.18 (4-2) M₁/M₃ 1.12 1.20 2.26 2.21 1.26 1.35  (5) nd_(2p) 1.946 2.002 2.002 2.002 2.144 2.144  (6) (r_(2na) + r_(2nb))/(r_(2na) − r_(2nb)) 0.82 0.95 0.87 0.87 0.85 0.86  (7) (r_(2nb) + r_(2pa))/(r_(2nb) − r_(2pa)) −6.51 −5.49 −5.30 −5.52 −6.02 −5.31  (8) (r_(1pa) + r_(1pb))/(r_(1pa) − r_(1pb)) −1.27 −1.48 −1.41 −1.40 −1.30 −1.34  (9) f₃/f_(W) 1.98 2.02 1.89 1.91 2.06 2.12 (10) f_(3IL)/f₃ 1.15 1.30 1.13 1.16 1.14 1.07 (11) f_(3n)/f₃ −0.54 −0.50 −0.68 −0.68 −0.57 −0.57

Numerical Example II-1

The zoom lens system of Numerical Example II-1 corresponds to Embodiment II-1 shown in FIG. 16. Table II-1 shows the surface data of the zoom lens system of Numerical Example II-1. Table II-2 shows the aspherical data. Table II-3 shows various data.

TABLE II-1 (Surface data) Surface number r d nd vd Object surface ∞  1 21.67895 0.80000 2.00170 20.6  2 16.21267 3.20000 1.72916 54.7  3 174.74440 Variable  4* −53.85976 1.10000 1.85976 40.6  5* 5.71997 0.92630  6 7.76084 1.70000 2.00170 20.6  7 16.00169 Variable  8(Diaphragm) ∞ 0.00000  9* 4.28080 2.50000 1.85135 40.1 10 7.80657 0.40000 2.00170 20.6 11 3.57214 0.50000 12 9.44005 1.50000 1.77250 49.6 13 214.22130 Variable 14* 12.42141 1.80000 1.62299 58.1 15 −75.23346 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE II-2 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 4.56239E−05, A6 = −6.94009E−07, A8 = 1.81220E−08 A10 = −8.02787E−11 Surface No. 5 K = −1.98341E+00, A4 = 1.07747E−03, A6 = −7.31374E−06, A8 = 1.86112E−07 A10 = 5.59108E−10 Surface No. 9 K = −3.53088E−01, A4 = 4.87967E−05, A6 = 2.95696E−05, A8 = −7.13705E−06 A10 = 7.21043E−07 Surface No. 14 K = 0.00000E+00, A4 = 6.02721E−05, A6 = 2.35414E−06, A8 = −1.45477E−07 A10 = 3.81222E−09

TABLE II-3 (Various data) Zooming ratio 6.58661 Wide-angle Middle Telephoto limit position limit Focal length 7.0002 17.9935 46.1078 F-number 3.42534 4.28755 5.96646 View angle 31.0628 12.2142 4.6470 Image height 3.8300 3.8300 3.8300 Overall length 41.8456 38.5980 53.0305 of lens system BF 0.50774 0.54740 0.50181 d3 0.6000 6.5818 17.3687 d7 16.6466 2.8215 1.0000 d13 2.3747 3.4807 17.1718 d15 6.2903 9.7403 1.5619 Entrance pupil 14.0988 19.1342 55.2858 position Exit pupil −15.3366 −21.2790 122.6438 position Front principal 18.0062 22.2940 118.7990 points position Back principal 34.8454 20.6045 6.9227 points position Single lens data Lens Initial surface Focal element number length 1 1 −69.2618 2 2 24.3018 3 4 −5.9634 4 6 13.6363 5 9 8.3957 6 10 −6.9006 7 12 12.7428 8 14 17.2488 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 38.69978 4.00000 −0.62539 1.15784 2 4 −10.96627 3.72630 0.32297 1.75775 3 8 13.67425 4.90000 −3.21446 −0.36143 4 14 17.24879 1.80000 0.15841 0.84054 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.45753 −0.60969 −1.52316 3 8 −0.77212 −2.46223 −0.99453 4 14 0.51204 0.30972 0.78651

Numerical Example II-2

The zoom lens system of Numerical Example II-2 corresponds to Embodiment II-2 shown in FIG. 18. Table II-4 shows the surface data of the zoom lens system of Numerical Example II-2. Table II-5 shows the aspherical data. Table II-6 shows various data.

TABLE II-4 (Surface data) Surface number r d nd vd Object surface ∞  1 22.20034 0.80000 1.92286 20.9  2 16.29755 3.20000 1.72916 54.7  3 139.18600 Variable  4* −59.14503 1.10000 1.85976 40.6  5* 5.94383 1.39250  6 8.10158 1.70000 1.94595 18.0  7 14.57504 Variable  8(Diaphragm) ∞ 0.00000  9* 4.39479 2.50000 1.85135 40.1 10 9.90230 0.40000 1.92286 20.9 11 3.68214 0.50000 12 10.58272 1.50000 1.77250 49.6 13 −59.81446 Variable 14* 14.64296 1.80000 1.62299 58.1 15 −81.51573 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE II-5 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 1.61461E−04, A6 = −3.32899E−06, A8 = 4.44142E−08 A10 = −2.25656E−10 Surface No. 5 K = −2.51025E+00, A4 = 1.41935E−03, A6 = −1.36992E−05, A8 = 1.83402E−07 A10 = 1.40309E−09 Surface No. 9 K = −4.30638E−01, A4 = 1.17618E−04, A6 = 2.71101E−05, A8 = −5.66873E−06 A10 = 6.02589E−07 Surface No. 14 K = 0.00000E+00, A4 = 5.90546E−05, A6 = 6.41505E−06, A8 = −3.18335E−07 A10 = 6.30964E−09

TABLE II-6 (Various data) Zooming ratio 6.54203 Wide-angle Middle Telephoto limit position limit Focal length 6.1188 12.9779 40.0295 F-number 3.23953 3.96695 5.67089 View angle 34.8313 16.7900 5.3897 Image height 3.8300 3.8300 3.8300 Overall length 41.5545 37.1082 52.5801 of lens system BF 0.50591 0.51794 0.52121 d3 0.6000 4.2068 17.3105 d7 16.5610 4.8693 1.0000 d13 2.3036 3.1689 16.2175 d15 5.6914 8.4528 1.6384 Entrance pupil 13.4247 15.7784 54.0064 position Exit pupil −14.4333 −18.8833 −435.0709 position Front principal 17.0374 20.0751 90.3573 points position Back principal 35.4356 24.1303 12.5506 points position Single lens data Lens Initial surface Focal element number length 1 1 −71.0393 2 2 25.0404 3 4 −6.2333 4 6 17.1001 5 9 7.6785 6 10 −6.5541 7 12 11.7490 8 14 20.0692 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 39.94948 4.00000 −0.67384 1.09928 2 4 −10.25874 4.19250 0.24741 1.66395 3 8 12.13874 4.90000 −2.11245 0.31040 4 14 20.06917 1.80000 0.17011 0.85302 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.39544 −0.45929 −1.11120 3 8 −0.63375 −1.49544 −1.11002 4 14 0.61117 0.47297 0.81236

Numerical Example II-3

The zoom lens system of Numerical Example II-3 corresponds to Embodiment II-3 shown in FIG. 21. Table II-7 shows the surface data of the zoom lens system of Numerical Example II-3. Table II-8 shows the aspherical data. Table II-9 shows various data.

TABLE II-7 (Surface data) Surface number r d nd vd Object surface ∞  1 20.56187 0.80000 1.92286 20.9  2 14.81270 3.20000 1.72916 54.7  3 158.73300 Variable  4* −59.17839 1.10000 1.85976 40.6  5* 5.51137 1.13160  6 7.62681 1.70000 1.94595 18.0  7 14.57504 Variable  8(Diaphragm) ∞ 0.00000  9* 4.20287 2.50000 1.85135 40.1 10 9.49076 0.40000 1.92286 20.9 11 3.47256 0.50000 12 9.45232 1.50000 1.77250 49.6 13 −630.07970 Variable 14* 12.45881 1.80000 1.62299 58.1 15 −53.07139 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE II-8 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 7.16481E−05, A6 = −9.20654E−07, A8 = 9.31422E−09 A10 = −1.08989E−11 Surface No. 5 K = −1.96424E+00, A4 = 1.20304E−03, A6 = −7.06323E−06, A8 = 1.22887E−07 A10 = 1.45469E−09 Surface No. 9 K = −4.49892E−01, A4 = 1.71358E−04, A6 = 2.95164E−05, A8 = −5.81944E−06 A10 = 6.34879E−07 Surface No. 14 K = 0.00000E+00, A4 = 3.68685E−05, A6 = 7.24260E−06, A8 = −3.15541E−07 A10 = 5.13901E−09

TABLE II-9 (Various data) Zooming ratio 6.52948 Wide-angle Middle Telephoto limit position limit Focal length 6.1187 12.9818 39.9518 F-number 3.12003 3.77592 5.46453 View angle 34.8394 16.8681 5.3822 Image height 3.8300 3.8300 3.8300 Overall length 40.0820 35.9984 50.0898 of lens system BF 0.50106 0.53718 0.50627 d3 0.6000 4.1205 15.5150 d7 15.7290 4.5669 1.0000 d13 2.2919 3.2444 15.6615 d15 5.3284 7.8978 1.7755 Entrance pupil 13.4079 15.7987 50.2041 position Exit pupil −14.5439 −19.3553 134.0690 position Front principal 17.0381 20.3085 102.1063 points position Back principal 33.9633 23.0165 10.1380 points position Single lens data Lens Initial surface Focal element number length 1 1 −61.5140 2 2 22.1975 3 4 −5.8185 4 6 15.1150 5 9 7.2781 6 10 −6.1295 7 12 12.0675 8 14 16.3687 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 35.95275 4.00000 −0.57161 1.19624 2 4 −9.80239 3.93160 0.32635 1.74700 3 8 12.20044 4.90000 −2.62124 0.03460 4 14 16.36872 1.80000 0.21311 0.89223 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.43721 −0.51865 −1.30606 3 8 −0.71015 −1.78990 −1.11238 4 14 0.54813 0.38896 0.76487

Numerical Example II-4

The zoom lens system of Numerical Example II-4 corresponds to Embodiment II-4 shown in FIG. 24. Table II-10 shows the surface data of the zoom lens system of Numerical Example II-4. Table II-11 shows the aspherical data. Table II-12 shows various data.

TABLE II-10 (Surface data) Surface number r d nd vd Object surface ∞  1 23.92026 0.80000 2.00170 20.6  2 17.23850 2.50000 1.80420 46.5  3* 91.93466 Variable  4* −86.26322 1.00000 1.85976 40.6  5* 5.30963 1.09570  6 7.43523 1.70000 2.00170 20.6  7 14.35270 Variable  8(Diaphragm) ∞ 0.00000  9* 4.78659 2.10000 1.77377 47.2 10 10.28002 0.80000 1.92286 20.9 11 4.30394 0.50000 12 11.80608 1.50000 1.80420 46.5 13 −41.97623 Variable 14* 18.23360 1.80000 1.80420 46.5 15 449.20610 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE II-11 (Aspherical data) Surface No. 3 K = 0.00000E+00, A4 = 1.16573E−06, A6 = 3.73564E−10, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 4 K = 0.00000E+00, A4 = 4.11218E−05, A6 = 4.14113E−07, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 5 K = −2.55557E+00, A4 = 1.78988E−03, A6 = −2.05242E−05, A8 = 4.89013E−07 A10 = 9.76558E−10 Surface No. 9 K = −4.57612E−01, A4 = 8.64666E−05, A6 = 3.31418E−05, A8 = −6.94709E−06 A10 = 6.20715E−07 Surface No. 14 K = 0.00000E+00, A4 = 3.07143E−05, A6 = 2.65662E−06, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE II-12 (Various data) Zooming ratio 6.54154 Wide-angle Middle Telephoto limit position limit Focal length 6.7983 17.3298 44.4713 F-number 3.35579 3.99862 4.53813 View angle 32.0536 12.6171 4.8991 Image height 3.8300 3.8300 3.8300 Overall length 40.9465 44.9233 56.8471 of lens system BF 0.50091 0.52914 0.50678 d3 0.6000 11.6273 24.8265 d7 15.2623 4.7479 1.4500 d13 2.5571 3.4896 12.7618 d15 7.2306 9.7337 2.5063 Entrance pupil 12.0260 31.2012 94.2363 position Exit pupil −15.9753 −20.1365 −50.5394 position Front principal 16.0192 33.9985 99.9644 points position Back principal 34.1483 27.5935 12.3759 points position Single lens data Lens Initial surface Focal element number length 1 1 −65.5343 2 2 25.9947 3 4 −5.7884 4 6 13.7142 5 9 9.9217 6 10 −8.5733 7 12 11.6022 8 14 23.5883 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 44.68006 3.30000 −0.90484 0.65703 2 4 −10.42881 3.79570 0.26532 1.66111 3 8 12.81592 4.90000 −1.39579 0.73000 4 14 23.58831 1.80000 −0.04213 0.76205 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.33923 −0.52896 −1.60039 3 8 −0.74721 −1.48745 −0.77711 4 14 0.60028 0.49297 0.80031

Numerical Example II-5

The zoom lens system of Numerical Example II-5 corresponds to Embodiment II-5 shown in FIG. 27. Table II-13 shows the surface data of the zoom lens system of Numerical Example II-5. Table II-14 shows the aspherical data. Table II-15 shows various data.

TABLE II-13 (Surface data) Surface number r d nd vd Object surface ∞  1 21.11164 0.80000 2.00170 20.6  2 15.12358 2.50000 1.80420 46.5  3* 88.24478 Variable  4* −69.21321 1.00000 1.85976 40.6  5* 4.93236 1.09570  6 7.22589 1.70000 2.00170 20.6  7 14.35270 Variable  8(Diaphragm) ∞ 0.00000  9* 4.94313 2.10000 1.77377 47.2 10 10.82877 0.80000 1.92286 20.9 11 4.47121 0.50000 12 11.90782 1.50000 1.80420 46.5 13 −39.79054 Variable 14* 20.42889 1.80000 1.80420 46.5 15 −248.53400 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE II-14 (Aspherical data) Surface No. 3 K = 0.00000E+00, A4 = 2.27928E−06, A6 = 3.00081E−10, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 4 K = 0.00000E+00, A4 = 5.20294E−05, A6 = −4.16769E−08, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 5 K = −2.47053E+00, A4 = 2.06679E−03, A6 = −2.74077E−05, A8 = 6.95651E−07 A10 = −4.23395E−09 Surface No. 9 K = −4.61701E−01, A4 = 8.60229E−05, A6 = 2.31646E−05, A8 = −4.52966E−06 A10 = 4.13883E−07 Surface No. 14 K = 0.00000E+00, A4 = 2.57276E−05, A6 = 3.06354E−06, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE II-15 (Various data) Zooming ratio 6.54191 Wide-angle Middle Telephoto limit position limit Focal length 6.7983 17.3294 44.4739 F-number 3.40234 3.91077 4.59471 View angle 32.0530 12.6173 4.9207 Image height 3.8300 3.8300 3.8300 Overall length 40.8782 44.9165 53.2755 of lens system BF 0.50271 0.52741 0.50364 d3 0.6000 11.2009 20.8199 d7 14.7539 5.4351 1.4500 d13 2.5571 3.2145 13.2000 d15 7.6688 9.7429 2.5063 Entrance pupil 11.7579 33.9417 82.6375 position Exit pupil −16.5435 −19.7880 −56.1280 position Front principal 15.8449 36.4888 92.1852 points position Back principal 34.0799 27.5871 8.8016 points position Single lens data Lens Initial surface Focal element number length 1 1 −57.0431 2 2 22.3546 3 4 −5.3221 4 6 12.9783 5 9 10.1707 6 10 −8.7828 7 12 11.5458 8 14 23.5435 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 38.26554 3.30000 −0.82482 0.73786 2 4 −9.46936 3.79570 0.23471 1.62366 3 8 12.87340 4.90000 −1.23135 0.84238 4 14 23.54354 1.80000 0.07600 0.87535 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.37282 −0.63989 −1.82826 3 8 −0.81370 −1.42546 −0.78982 4 14 0.58564 0.49650 0.80488

Numerical Example II-6

The zoom lens system of Numerical Example II-6 corresponds to Embodiment II-6 shown in FIG. 30. Table II-16 shows the surface data of the zoom lens system of Numerical Example II-6. Table II-17 shows the aspherical data. Table II-18 shows various data.

TABLE II-16 (Surface data) Surface number r d nd vd Object surface ∞  1 22.01411 0.80000 2.14422 17.5  2 16.76615 2.50000 1.82080 42.7  3* 101.42760 Variable  4* −71.58793 1.00000 1.85976 40.6  5* 5.13092 1.09570  6 7.40182 1.70000 2.00170 20.6  7 14.35270 Variable  8(Diaphragm) ∞ 0.00000  9* 4.80218 2.10000 1.77377 47.2 10 9.87535 0.80000 1.92286 20.9 11 4.30138 0.50000 12 11.64846 1.50000 1.80420 46.5 13 −48.27259 Variable 14* 19.51788 1.30000 1.80420 46.5 15 −601.21670 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE II-17 (Aspherical data) Surface No. 3 K = 0.00000E+00, A4 = 1.96399E−06, A6 = 8.38790E−10, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 4 K = 0.00000E+00, A4 = 2.08635E−05, A6 = 4.82445E−07, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 5 K = −2.72794E+00, A4 = 2.05037E−03, A6 = −3.37206E−05, A8 = 8.72404E−07 A10 = −5.23638E−09 Surface No. 9 K = −4.61942E−01, A4 = 1.03075E−04, A6 = 2.43831E−05, A8 = −4.51015E−06 A10 = 4.15499E−07 Surface No. 14 K = 0.00000E+00, A4 = 2.82102E−05, A6 = 3.05454E−06, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE II-18 (Various data) Zooming ratio 6.54969 Wide-angle Middle Telephoto limit position limit Focal length 6.7999 17.3217 44.5372 F-number 3.42679 4.00985 4.56886 View angle 32.0408 12.5843 4.9066 Image height 3.8300 3.8300 3.8300 Overall length 41.1512 44.8950 53.2882 of lens system BF 0.50957 0.51183 0.52021 d3 0.6000 10.9391 21.3625 d7 15.4165 5.6233 1.3000 d13 2.4448 3.4802 12.6158 d15 7.8846 10.0448 3.1939 Entrance pupil 11.9887 32.6384 82.8481 position Exit pupil −16.1869 −20.1889 −50.2594 position Front principal 16.0192 35.4659 88.3232 points position Back principal 34.3513 27.5733 8.7510 points position Single lens data Lens Initial surface Focal element number length 1 1 −66.9089 2 2 24.1504 3 4 −5.5354 4 6 13.5941 5 9 10.2331 6 10 −8.8686 7 12 11.8005 8 14 23.5288 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 39.22731 3.30000 −0.83975 0.75865 2 4 −9.73077 3.79570 0.26561 1.66074 3 8 13.01946 4.90000 −1.48970 0.66880 4 14 23.52878 1.30000 0.02268 0.60146 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.37298 −0.61781 −1.82667 3 8 −0.79375 −1.44795 −0.79235 4 14 0.58553 0.49362 0.78444

Numerical Example II-7

The zoom lens system of Numerical Example II-7 corresponds to Embodiment II-7 shown in FIG. 32. Table II-19 shows the surface data of the zoom lens system of Numerical Example II-7. Table II-20 shows the aspherical data. Table II-21 shows various data.

TABLE II-19 (Surface data) Surface number r d nd vd Object surface ∞  1 25.31776 0.80000 1.92286 20.9  2 18.23858 2.90000 1.77250 49.6  3 141.43600 Variable  4* −74.12426 0.95000 1.85976 40.6  5* 5.92627 1.47140  6 8.28920 1.70000 2.14422 17.5  7 12.83109 Variable  8(Diaphragm) ∞ 0.00000  9* 4.63999 2.45000 1.80139 45.4 10 11.40598 0.50000 1.92286 20.9 11 4.08736 0.48000 12 11.58038 1.50000 1.80420 46.5 13 −46.42335 Variable 14* 16.70893 1.70000 1.80610 40.7 15 −271.10350 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE II-20 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 8.00930E−05, A6 = −8.24171E−07, A8 = 7.02480E−09 A10 = 0.00000E+00 Surface No. 5 K = −2.80748E+00, A4 = 1.51170E−03, A6 = −1.93182E−05, A8 = 3.79463E−07 A10 = −1.27953E−09 Surface No. 9 K = −3.81122E−01, A4 = 1.92672E−05, A6 = 2.36355E−05, A8 = −5.76293E−06 A10 = 5.76364E−07 Surface No. 14 K = 0.00000E+00, A4 = 5.48957E−05, A6 = 4.00480E−07, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE II-21 (Various data) Zooming ratio 6.54099 Wide-angle Middle Telephoto limit position limit Focal length 6.1338 15.6371 40.1213 F-number 3.35969 3.84965 5.84335 View angle 35.0631 13.8718 5.4025 Image height 3.8300 3.8300 3.8300 Overall length 43.0188 45.0018 57.0268 of lens system BF 0.49471 0.53782 0.50457 d3 0.5000 11.4355 18.9917 d7 17.0651 5.3765 1.4500 d13 3.8959 4.3424 17.9582 d15 5.6117 7.8582 2.6709 Entrance pupil 12.7522 32.7502 57.3438 position Exit pupil −17.6154 −20.9508 309.8164 position Front principal 16.8085 37.0083 102.6693 points position Back principal 36.8850 29.3648 16.9055 points position Single lens data Lens Initial surface Focal element number length 1 1 −74.7335 2 2 26.8298 3 4 −6.3478 4 6 17.0587 5 9 8.4064 6 10 −7.1366 7 12 11.6594 8 14 19.5762 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 43.09186 3.70000 −0.63212 1.04900 2 4 −10.40411 4.12140 0.28566 1.75797 3 8 12.61365 4.93000 −1.72530 0.54757 4 14 19.57623 1.70000 0.05479 0.81105 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.35568 −0.56805 −0.96698 3 8 −0.65716 −1.29835 −1.26908 4 14 0.60898 0.49202 0.75870

Numerical Example II-8

The zoom lens system of Numerical Example II-8 corresponds to Embodiment II-8 shown in FIG. 34. Table II-22 shows the surface data of the zoom lens system of Numerical Example II-8. Table II-23 shows the aspherical data. Table II-24 shows various data.

TABLE II-22 (Surface data) Surface number r d nd vd Object surface ∞  1 25.31390 0.80000 1.92286 20.9  2 18.37307 2.90000 1.77250 49.6  3 127.09120 Variable  4* −72.33967 0.95000 1.85976 40.6  5* 5.53361 1.50880  6 8.10144 1.70000 2.14422 17.5  7 12.83109 Variable  8(Diaphragm) ∞ 0.00000  9* 4.58126 2.45000 1.80139 45.4 10 12.89458 0.50000 1.92286 20.9 11 4.09435 0.48000 12 12.11282 1.50000 1.80420 46.5 13 −29.99816 Variable 14* 16.30826 1.70000 1.82080 42.7 15 −204.49060 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE II-23 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 1.38654E−04, A6 = −2.03482E−06, A8 = 1.30075E−08 A10 = 0.00000E+00 Surface No. 5 K = −2.38369E+00, A4 = 1.55078E−03, A6 = −1.46113E−05, A8 = 2.67367E−07 A10 = −2.02236E−09 Surface No. 9 K = −4.10236E−01, A4 = 2.02270E−05, A6 = 2.52654E−05, A8 = −7.12069E−06 A10 = 8.11753E−07 Surface No. 14 K = 0.00000E+00, A4 = 5.64788E−05, A6 = 4.75905E−07, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE II-24 (Various data) Zooming ratio 6.54149 Wide-angle Middle Telephoto limit position limit Focal length 5.5377 14.1127 36.2248 F-number 3.29490 3.84420 5.79699 View angle 37.8649 15.3659 5.9868 Image height 3.8300 3.8300 3.8300 Overall length 41.5403 44.0499 56.5476 of lens system BF 0.51202 0.52769 0.52473 d3 0.5000 11.0956 19.1926 d7 16.2704 5.0362 1.4500 d13 3.8899 4.8390 17.2154 d15 4.8791 7.0627 2.6761 Entrance pupil 12.0360 30.5678 56.7404 position Exit pupil −17.3975 −22.2119 209.0752 position Front principal 15.8615 35.9218 99.2574 points position Back principal 36.0026 29.9372 20.3228 points position Single lens data Lens Initial surface Focal element number length 1 1 −76.8613 2 2 27.4838 3 4 −5.9453 4 6 16.1170 5 9 7.8392 6 10 −6.6830 7 12 10.9026 8 14 18.4654 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 44.06577 3.70000 −0.70119 0.98430 2 4 −9.81147 4.15880 0.22506 1.68504 3 8 11.74129 4.93000 −1.33477 0.80049 4 14 18.46535 1.70000 0.06920 0.83229 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.31841 −0.48529 −0.80946 3 8 −0.63113 −1.30361 −1.36507 4 14 0.62535 0.50625 0.74396

The following Table II-25 shows the corresponding values to the individual conditions in the zoom lens systems of each of Numerical Examples.

TABLE II-25 (Values corresponding to conditions) Example Condition II-1 II-2 II-3 II-4 II-5 II-6 II-7 II-8 (3-2) (β_(2T)/β_(2W))/(β_(3T)/β_(3W)) 2.58 1.60 1.91 4.54 5.05 4.91 1.41 1.18 (b-1) f_(T)/f_(W) 6.59 6.54 6.53 6.54 6.54 6.55 6.54 6.54 (a-2) ω_(W) 31.08 34.84 34.84 32.05 32.06 32.05 35.06 37.88 (2-2) f₂/f_(W) −1.57 −1.68 −1.60 −1.53 −1.39 −1.43 −1.70 −1.77 (4-2) M₁/M₃ 1.11 1.12 1.02 2.90 2.26 2.21 1.26 1.35  (5) nd_(2p) 2.002 1.946 1.946 2.002 2.002 2.002 2.144 2.144  (6) (r_(2na) + r_(2nb))/(r_(2na) − r_(2nb)) 0.81 0.82 0.83 0.88 0.87 0.87 0.85 0.86  (7) (r_(2nb) + r_(2pa))/(r_(2nb) − r_(2pa)) −6.61 −6.51 −6.21 −6.00 −5.30 −5.52 −6.02 −5.31  (8) (r_(1pa) + r_(1pb))/(r_(1pa) − r_(1pb)) −1.20 −1.27 −1.21 −1.46 −1.41 −1.40 −1.30 −1.34  (9) f₃/f_(W) 1.95 1.98 1.99 1.89 1.89 1.91 2.06 2.12 (10) f_(3IL)/f₃ 1.25 1.15 1.18 1.14 1.13 1.16 1.14 1.07 (11) f_(3n)/f₃ −0.50 −0.54 −0.50 −0.67 −0.68 −0.68 −0.57 −0.57

Numerical Example III-1

The zoom lens system of Numerical Example III-1 corresponds to Embodiment III-1 shown in FIG. 37. Table III-1 shows the surface data of the zoom lens system of Numerical Example III-1. Table III-2 shows the aspherical data. Table III-3 shows various data.

TABLE III-1 (Surface data) Surface number r d nd vd Object surface ∞  1 22.52601 0.80000 1.92286 20.9  2 16.32565 3.20000 1.72916 54.7  3 207.73150 Variable  4* −58.88450 1.10000 1.85976 40.6  5* 6.29064 1.27740  6 8.20213 1.70000 1.94595 18.0  7 14.57504 Variable  8(Diaphragm) ∞ 0.00000  9* 4.28717 2.50000 1.85135 40.1 10 8.64793 0.40000 1.92286 20.9 11 3.51077 0.50000 12 9.89324 1.50000 1.77250 49.6 13 270.24380 Variable 14* 11.85559 1.80000 1.62299 58.1 15 −149.18250 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE III-2 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 1.54676E−04, A6 = −4.85701E−06, A8 = 9.08996E−08 A10 = −5.94484E−10 Surface No. 5 K = −3.54307E+00, A4 = 1.75093E−03, A6 = −3.51461E−05, A8 = 7.02807E−07 A10 = −2.85240E−09 Surface No. 9 K = −4.49859E−01, A4 = 1.95364E−04, A6 = 3.06104E−05, A8 = −5.88023E−06 A10 = 6.62772E−07 Surface No. 14 K = 0.00000E+00, A4 = −2.47044E−05, A6 = 1.82158E−05, A8 = −1.04997E−06 A10 = 2.22666E−08

TABLE III-3 (Various data) Zooming ratio 6.54045 Wide-angle Middle Telephoto limit position limit Focal length 6.7980 14.4234 44.4619 F-number 3.39347 4.04095 5.95026 View angle 31.8253 15.2211 4.8154 Image height 3.8300 3.8300 3.8300 Overall length 41.8818 41.2742 52.8975 of lens system BF 0.48940 0.49563 0.49986 d3 0.6000 6.5818 17.0242 d7 16.5617 6.2213 1.0000 d13 2.2867 4.3897 17.0896 d15 6.1665 7.8084 1.5064 Entrance pupil 14.0166 22.5786 54.5990 position Exit pupil −14.9034 −21.4736 161.1283 position Front principal 17.8124 27.5327 111.3679 points position Back principal 35.0838 26.8508 8.4356 points position Single lens data Lens Initial surface Focal element number length 1 1 −68.5116 2 2 24.1292 3 4 −6.5594 4 6 17.5542 5 9 7.9030 6 10 −6.6527 7 12 13.2601 8 14 17.7050 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 38.39330 4.00000 −0.49622 1.26336 2 4 −10.80549 4.07740 0.32173 1.75074 3 8 13.40495 4.90000 −3.09913 −0.28853 4 14 17.70499 1.80000 0.08200 0.76816 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.45156 −0.60206 −1.43973 3 8 −0.74187 −1.43294 −1.01668 4 14 0.52855 0.43546 0.79117

Numerical Example III-2

The zoom lens system of Numerical Example III-2 corresponds to Embodiment III-2 shown in FIG. 39. Table III-4 shows the surface data of the zoom lens system of Numerical Example III-2. Table III-5 shows the aspherical data. Table III-6 shows various data.

TABLE III-4 (Surface data) Surface number r d nd vd Object surface ∞  1 20.56187 0.80000 1.92286 20.9  2 14.81270 3.20000 1.72916 54.7  3 158.73300 Variable  4* −59.17839 1.10000 1.85976 40.6  5* 5.51137 1.13160  6 7.62681 1.70000 1.94595 18.0  7 14.57504 Variable  8(Diaphragm) ∞ 0.00000  9* 4.20287 2.50000 1.85135 40.1 10 9.49076 0.40000 1.92286 20.9 11 3.47256 0.50000 12 9.45232 1.50000 1.77250 49.6 13 −630.07970 Variable 14* 12.45881 1.80000 1.62299 58.1 15 −53.07139 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE III-5 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 7.16481E−05, A6 = −9.20654E−07, A8 = 9.31422E−09 A10 = −1.08989E−11 Surface No. 5 K = −1.96424E+00, A4 = 1.20304E−03, A6 = −7.06323E−06, A8 = 1.22887E−07 A10 = 1.45469E−09 Surface No. 9 K = −4.49892E−01, A4 = 1.71358E−04, A6 = 2.95164E−05, A8 = −5.81944E−06 A10 = 6.34879E−07 Surface No. 14 K = 0.00000E+00, A4 = 3.68685E−05, A6 = 7.24260E−06, A8 = −3.15541E−07 A10 = 5.13901E−09

TABLE III-6 (Various data) Zooming ratio 6.52948 Wide-angle Middle Telephoto limit position limit Focal length 6.1187 12.9818 39.9518 F-number 3.12003 3.77592 5.46453 View angle 34.8394 16.8681 5.3822 Image height 3.8300 3.8300 3.8300 Overall length 40.0820 35.9984 50.0898 of lens system BF 0.50106 0.53718 0.50627 d3 0.6000 4.1205 15.5150 d7 15.7290 4.5669 1.0000 d13 2.2919 3.2444 15.6615 d15 5.3284 7.8978 1.7755 Entrance pupil 13.4079 15.7987 50.2041 position Exit pupil −14.5439 −19.3553 134.0690 position Front principal 17.0381 20.3085 102.1063 points position Back principal 33.9633 23.0165 10.1380 points position Single lens data Lens Initial surface Focal element number length 1 1 −61.5140 2 2 22.1975 3 4 −5.8185 4 6 15.1150 5 9 7.2781 6 10 −6.1295 7 12 12.0675 8 14 16.3687 Zoom lens unit data Lens Initial Focal Overall length Front principal Back principal unit surface No. length of lens unit points position points position 1 1 35.95275 4.00000 −0.57161 1.19624 2 4 −9.80239 3.93160 0.32635 1.74700 3 8 12.20044 4.90000 −2.62124 0.03460 4 14 16.36872 1.80000 0.21311 0.89223 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.43721 −0.51865 −1.30606 3 8 −0.71015 −1.78990 −1.11238 4 14 0.54813 0.38896 0.76487

Numerical Example III-3

The zoom lens system of Numerical Example III-3 corresponds to Embodiment III-3 shown in FIG. 42. Table III-7 shows the surface data of the zoom lens system of Numerical Example III-3. Table III-8 shows the aspherical data. Table III-9 shows various data.

TABLE III-7 (Surface data) Surface number r d nd vd Object surface ∞  1 24.21902 0.80000 1.92286 20.9  2 17.02733 3.00000 1.77250 49.6  3 141.43600 Variable  4* −74.12426 1.00000 1.85976 40.6  5* 5.93476 1.39220  6 8.14754 1.70000 1.94595 18.0  7 14.57504 Variable  8(Diaphragm) ∞ 0.00000  9* 4.60150 2.50000 1.77377 47.2 10 13.28805 0.40000 1.84666 23.8 11 4.00087 0.50000 12 11.41115 1.50000 1.80420 46.5 13 −89.00278 Variable 14* 14.81798 1.80000 1.58913 61.3 15 −135.33920 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE III-8 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 3.17769E−05, A6 = 2.52415E−07, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 5 K = −2.05246E+00, A4 = 1.03297E−03, A6 = −6.21595E−06, A8 = 1.71504E−07 A10 = 9.00685E−10 Surface No. 9 K = −3.68884E−01, A4 = 4.03259E−05, A6 = 1.87605E−05, A8 = −4.20225E−06 A10 = 3.87468E−07 Surface No. 14 K = 0.00000E+00, A4 = 5.68131E−05, A6 = 5.49828E−07, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE III-9 (Various data) Zooming ratio 6.53845 Wide-angle Middle Telephoto limit position limit Focal length 6.7994 17.3321 44.4573 F-number 3.53136 4.13883 6.02867 View angle 32.0505 12.5574 4.8706 Image height 3.8300 3.8300 3.8300 Overall length 44.4149 45.3982 57.3942 of lens system BF 0.49954 0.53445 0.50459 d3 0.5000 10.2297 18.3237 d7 17.4263 5.3660 1.4500 d13 3.9465 4.4359 18.9880 d15 6.4503 9.2400 2.5357 Entrance pupil 13.0906 30.2684 57.6472 position Exit pupil −18.0633 −21.8942 −616.8088 position Front principal 17.3994 34.2068 98.9028 points position Back principal 37.6156 28.0661 12.9369 points position Single lens data Lens Initial surface Focal element number length 1 1 −65.6394 2 2 24.7980 3 4 −6.3544 4 6 17.3061 5 9 8.0824 6 10 −6.8974 7 12 12.6612 8 14 22.7714 Zoom lens unit data Initial Overall Lens surface Focal length of Front principal Back principal unit No. length lens unit points position points position 1 1 41.13377 3.80000 −0.62624 1.10007 2 4 −10.47225 4.09220 0.22232 1.59429 3 8 13.29663 4.90000 −1.92701 0.36187 4 14 22.77144 1.80000 0.11228 0.77452 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.38445 −0.59809 −1.11222 3 8 −0.69257 −1.41819 −1.22617 4 14 0.62081 0.49677 0.79250

Numerical Example III-4

The zoom lens system of Numerical Example III-4 corresponds to Embodiment III-4 shown in FIG. 45. Table III-10 shows the surface data of the zoom lens system of Numerical Example III-4. Table III-11 shows the aspherical data. Table III-12 shows various data.

TABLE III-10 (Surface data) Surface number r d nd vd Object surface ∞  1 23.92026 0.80000 2.00170 20.6  2 17.23850 2.50000 1.80420 46.5  3* 91.93466 Variable  4* −86.26322 1.00000 1.85976 40.6  5* 5.30963 1.09570  6 7.43523 1.70000 2.00170 20.6  7 14.35270 Variable  8(Diaphragm) ∞ 0.00000  9* 4.78659 2.10000 1.77377 47.2 10 10.28002 0.80000 1.92286 20.9 11 4.30394 0.50000 12 11.80608 1.50000 1.80420 46.5 13 −41.97623 Variable 14* 18.23360 1.80000 1.80420 46.5 15 449.20610 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE III-11 (Aspherical data) Surface No. 3 K = 0.00000E+00, A4 = 1.16573E−06, A6 = 3.73564E−10, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 4 K = 0.00000E+00, A4 = 4.11218E−05, A6 = 4.14113E−07, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 5 K = −2.55557E+00, A4 = 1.78988E−03, A6 = −2.05242E−05, A8 = 4.89013E−07 A10 = 9.76558E−10 Surface No. 9 K = −4.57612E−01, A4 = 8.64666E−05, A6 = 3.31418E−05, A8 = −6.94709E−06 A10 = 6.20715E−07 Surface No. 14 K = 0.00000E+00, A4 = 3.07143E−05, A6 = 2.65662E−06, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE III-12 (Various data) Zooming ratio 6.54154 Wide-angle Middle Telephoto limit position limit Focal length 6.7983 17.3298 44.4713 F-number 3.35579 3.99862 4.53813 View angle 32.0536 12.6171 4.8991 Image height 3.8300 3.8300 3.8300 Overall length 40.9465 44.9233 56.8471 of lens system BF 0.50091 0.52914 0.50678 d3 0.6000 11.6273 24.8265 d7 15.2623 4.7479 1.4500 d13 2.5571 3.4896 12.7618 d15 7.2306 9.7337 2.5063 Entrance pupil 12.0260 31.2012 94.2363 position Exit pupil −15.9753 −20.1365 −50.5394 position Front principal 16.0192 33.9985 99.9644 points position Back principal 34.1483 27.5935 12.3759 points position Single lens data Lens Initial surface Focal element number length 1 1 −65.5343 2 2 25.9947 3 4 −5.7884 4 6 13.7142 5 9 9.9217 6 10 −8.5733 7 12 11.6022 8 14 23.5883 Zoom lens unit data Initial Overall Lens surface Focal length of Front principal Back principal unit No. length lens unit points position points position 1 1 44.68006 3.30000 −0.90484 0.65703 2 4 −10.42881 3.79570 0.26532 1.66111 3 8 12.81592 4.90000 −1.39579 0.73000 4 14 23.58831 1.80000 −0.04213 0.76205 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.33923 −0.52896 −1.60039 3 8 −0.74721 −1.48745 −0.77711 4 14 0.60028 0.49297 0.80031

Numerical Example III-5

The zoom lens system of Numerical Example III-5 corresponds to Embodiment III-5 shown in FIG. 48. Table III-13 shows the surface data of the zoom lens system of Numerical Example III-5. Table III-14 shows the aspherical data. Table III-15 shows various data.

TABLE III-13 (Surface data) Surface number r d nd vd Object surface ∞  1 21.11164 0.80000 2.00170 20.6  2 15.12358 2.50000 1.80420 46.5  3* 88.24478 Variable  4* −69.21321 1.00000 1.85976 40.6  5* 4.93236 1.09570  6 7.22589 1.70000 2.00170 20.6  7 14.35270 Variable  8(Diaphragm) ∞ 0.00000  9* 4.94313 2.10000 1.77377 47.2 10 10.82877 0.80000 1.92286 20.9 11 4.47121 0.50000 12 11.90782 1.50000 1.80420 46.5 13 −39.79054 Variable 14* 20.42889 1.80000 1.80420 46.5 15 −248.53400 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE III-14 (Aspherical data) Surface No. 3 K = 0.00000E+00, A4 = 2.27928E−06, A6 = 3.00081E−10, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 4 K = 0.00000E+00, A4 = 5.20294E−05, A6 = −4.16769E−08, A8 = 0.00000E+00 A10 = 0.00000E+00 Surface No. 5 K = −2.47053E+00, A4 = 2.06679E−03, A6 = −2.74077E−05, A8 = 6.95651E−07 A10 = −4.23395E−09 Surface No. 9 K = −4.61701E−01, A4 = 8.60229E−05, A6 = 2.31646E−05, A8 = −4.52966E−06 A10 = 4.13883E−07 Surface No. 14 K = 0.00000E+00, A4 = 2.57276E−05, A6 = 3.06354E−06, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE III-15 (Various data) Zooming ratio 6.54191 Wide-angle Middle Telephoto limit position limit Focal length 6.7983 17.3294 44.4739 F-number 3.40234 3.91077 4.59471 View angle 32.0530 12.6173 4.9207 Image height 3.8300 3.8300 3.8300 Overall length 40.8782 44.9165 53.2755 of lens system BF 0.50271 0.52741 0.50364 d3 0.6000 11.2009 20.8199 d7 14.7539 5.4351 1.4500 d13 2.5571 3.2145 13.2000 d15 7.6688 9.7429 2.5063 Entrance pupil 11.7579 33.9417 82.6375 position Exit pupil −16.5435 −19.7880 −56.1280 position Front principal 15.8449 36.4888 92.1852 points position Back principal 34.0799 27.5871 8.8016 points position Single lens data Lens Initial surface Focal element number length 1 1 −57.0431 2 2 22.3546 3 4 −5.3221 4 6 12.9783 5 9 10.1707 6 10 −8.7828 7 12 11.5458 8 14 23.5435 Zoom lens unit data Initial Overall Lens surface Focal length of Front principal Back principal unit No. length lens unit points position points position 1 1 38.26554 3.30000 −0.82482 0.73786 2 4 −9.46936 3.79570 0.23471 1.62366 3 8 12.87340 4.90000 −1.23135 0.84238 4 14 23.54354 1.80000 0.07600 0.87535 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.37282 −0.63989 −1.82826 3 8 −0.81370 −1.42546 −0.78982 4 14 0.58564 0.49650 0.80488

Numerical Example III-6

The zoom lens system of Numerical Example III-6 corresponds to Embodiment III-6 shown in FIG. 51. Table III-16 shows the surface data of the zoom lens system of Numerical Example III-6. Table III-17 shows the aspherical data. Table III-18 shows various data.

TABLE III-16 (Surface data) Surface number r d nd vd Object surface ∞  1 24.63915 0.80000 1.92286 20.9  2 17.69162 2.90000 1.77250 49.6  3 141.43600 Variable  4* −74.12426 0.95000 1.85976 40.6  5* 5.96172 1.39660  6 8.26210 1.70000 2.14422 17.5  7 12.83109 Variable  8(Diaphragm) ∞ 0.00000  9* 4.65521 2.50090 1.80139 45.4 10 11.21394 0.50000 1.92286 20.9 11 4.06867 0.50000 12 11.22865 1.50000 1.80420 46.5 13 −68.81526 Variable 14* 15.96294 1.70000 1.80610 40.7 15 −270.01270 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE III-17 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 3.83404E−05, A6 = 5.29405E−08, A8 = 1.02032E−09 A10 = 0.00000E+00 Surface No. 5 K = −3.21567E+00, A4 = 1.68391E−03, A6 = −3.06050E−05, A8 = 7.28861E−07 A10 = −5.38787E−09 Surface No. 9 K = −3.45514E−01, A4 = −2.07950E−05, A6 = 2.45075E−05, A8 = −6.29992E−06 A10 = 6.15382E−07 Surface No. 14 K = 0.00000E+00, A4 = 5.07793E−05, A6 = 3.47763E−07, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE III-18 (Various data) Zooming ratio 6.54156 Wide-angle Middle Telephoto limit position limit Focal length 6.4574 16.4623 42.2414 F-number 3.43301 3.85000 5.93349 View angle 33.6879 13.1888 5.1236 Image height 3.8300 3.8300 3.8300 Overall length 43.0231 45.0104 57.0342 of lens system BF 0.49458 0.54184 0.50628 d3 0.5000 11.6929 18.6778 d7 16.7547 5.2707 1.4500 d13 3.9231 3.9579 18.3061 d15 5.9032 8.0996 2.6465 Entrance pupil 12.9125 34.3781 57.9941 position Exit pupil −18.2489 −20.5320 155.8859 position Front principal 17.1452 37.9805 111.7193 points position Back principal 36.5657 28.5482 14.7928 points position Single lens data Lens Initial surface Focal element number length 1 1 −71.9643 2 2 25.9114 3 4 −6.3830 4 6 16.9188 5 9 8.4915 6 10 −7.1597 7 12 12.1049 8 14 18.7469 Zoom lens unit data Initial Overall Lens surface Focal length of Front principal Back principal unit No. length lens unit points position points position 1 1 41.71577 3.70000 −0.61640 1.06461 2 4 −10.48715 4.04660 0.32254 1.79750 3 8 13.07665 5.00090 −1.99839 0.39268 4 14 18.74694 1.70000 0.05268 0.80892 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.37763 −0.63260 −1.09323 3 8 −0.71161 −1.36698 −1.23644 4 14 0.57603 0.45635 0.74913

Numerical Example III-7

The zoom lens system of Numerical Example III-7 corresponds to Embodiment III-7 shown in FIG. 53. Table III-19 shows the surface data of the zoom lens system of Numerical Example III-7. Table III-20 shows the aspherical data. Table III-21 shows various data.

TABLE III-19 (Surface data) Surface number r d nd vd Object surface ∞  1 25.31390 0.80000 1.92286 20.9  2 18.37307 2.90000 1.77250 49.6  3 127.09120 Variable  4* −72.33967 0.95000 1.85976 40.6  5* 5.53361 1.50880  6 8.10144 1.70000 2.14422 17.5  7 12.83109 Variable  8(Diaphragm) ∞ 0.00000  9* 4.58126 2.45000 1.80139 45.4 10 12.89458 0.50000 1.92286 20.9 11 4.09435 0.48000 12 12.11282 1.50000 1.80420 46.5 13 −29.99816 Variable 14* 16.30826 1.70000 1.82080 42.7 15 −204.49060 Variable 16 ∞ 1.00000 1.51680 64.2 17 ∞ (BF) Image surface ∞

TABLE III-20 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 = 1.38654E−04, A6 = −2.03482E−06, A8 = 1.30075E−08 A10 = 0.00000E+00 Surface No. 5 K = −2.38369E+00, A4 = 1.55078E−03, A6 = −1.46113E−05, A8 = 2.67367E−07 A10 = −2.02236E−09 Surface No. 9 K = −4.10236E−01, A4 = 2.02270E−05, A6 = 2.52654E−05, A8 = −7.12069E−06 A10 = 8.11753E−07 Surface No. 14 K = 0.00000E+00, A4 = 5.64788E−05, A6 = 4.75905E−07, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE III-21 (Various data) Zooming ratio 6.54149 Wide-angle Middle Telephoto limit position limit Focal length 5.5377 14.1127 36.2248 F-number 3.29490 3.84420 5.79699 View angle 37.8649 15.3659 5.9868 Image height 3.8300 3.8300 3.8300 Overall length 41.5403 44.0499 56.5476 of lens system BF 0.51202 0.52769 0.52473 d3 0.5000 11.0956 19.1926 d7 16.2704 5.0362 1.4500 d13 3.8899 4.8390 17.2154 d15 4.8791 7.0627 2.6761 Entrance pupil 12.0360 30.5678 56.7404 position Exit pupil −17.3975 −22.2119 209.0752 position Front principal 15.8615 35.9218 99.2574 points position Back principal 36.0026 29.9372 20.3228 points position Single lens data Lens Initial surface Focal element number length 1 1 −76.8613 2 2 27.4838 3 4 −5.9453 4 6 16.1170 5 9 7.8392 6 10 −6.6830 7 12 10.9026 8 14 18.4654 Zoom lens unit data Initial Overall Lens surface Focal length of Front principal Back principal unit No. length lens unit points position points position 1 1 44.06577 3.70000 −0.70119 0.98430 2 4 −9.81147 4.15880 0.22506 1.68504 3 8 11.74129 4.93000 −1.33477 0.80049 4 14 18.46535 1.70000 0.06920 0.83229 Magnification of zoom lens unit Lens Initial Wide-angle Middle Telephoto unit surface No. limit position limit 1 1 0.00000 0.00000 0.00000 2 4 −0.31841 −0.48529 −0.80946 3 8 −0.63113 −1.30361 −1.36507 4 14 0.62535 0.50625 0.74396

The following Table III-22 shows the corresponding values to the individual conditions in the zoom lens systems of each of Numerical Examples.

TABLE III-22 (Values corresponding to conditions) Example Condition III-1 III-2 III-3 III-4 III-5 III-6 III-7 (4-2) M₁/M₃ 1.08 1.02 1.17 2.90 2.26 1.26 1.35 (b-1) f_(T)/f_(W) 6.54 6.53 6.54 6.54 6.54 6.54 6.54 (a-2) ω_(W) 31.81 34.84 32.05 32.05 32.06 33.68 37.88 (2-2) f₂/f_(W) −1.59 −1.60 −1.54 −1.53 −1.39 −1.62 −1.77 (3-2) (β_(2T)/β_(2W))/(β_(3T)/β_(3W)) 2.33 1.91 1.63 4.54 5.05 1.67 1.18  (5) nd_(2p) 1.946 1.946 1.946 2.002 2.002 2.144 2.144  (6) (r_(2na) + r_(2nb))/(r_(2na) − r_(2nb)) 0.81 0.83 0.85 0.88 0.87 0.85 0.86  (7) (r_(2nb) + r_(2pa))/(r_(2nb) − r_(2pa)) −7.58 −6.21 −6.36 −6.00 −5.30 −6.18 −5.31  (8) (r_(1pa) + r_(1pb))/(r_(1pa) − r_(1pb)) −1.17 −1.21 −1.27 −1.46 −1.41 −1.29 −1.34  (9) f₃/f_(W) 1.97 1.99 1.96 1.89 1.89 2.03 2.12 (10) f_(3IL)/f₃ 1.30 1.18 1.24 1.14 1.13 1.19 1.07 (11) f_(3n)/f₃ −0.50 −0.50 −0.52 −0.67 −0.68 −0.55 −0.57

INDUSTRIAL APPLICABILITY

The zoom lens system according to the present invention is applicable to a digital input device such as a digital camera, a mobile telephone, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a Web camera or a vehicle-mounted camera. In particular, the zoom lens system according to the present invention is suitable for a photographing optical system where high image quality is required like in a digital camera.

DESCRIPTION OF THE REFERENCE CHARACTERS

-   -   G1 first lens unit     -   G2 second lens unit     -   G3 third lens unit     -   G4 fourth lens unit     -   L1 first lens element     -   L2 second lens element     -   L3 third lens element     -   L4 fourth lens element     -   L5 fifth lens element     -   L6 sixth lens element     -   L7 seventh lens element     -   L8 eighth lens element     -   A aperture diaphragm     -   P plane parallel plate     -   S image surface     -   1 zoom lens system     -   2 image sensor     -   3 liquid crystal display monitor     -   4 body     -   5 main barrel     -   6 moving barrel     -   7 cylindrical cam 

1. A zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and the following conditions (2-2), (b-1) and (a-2) are satisfied: −2.0<f ₂ /f _(W)<−1.1  (2-2) f _(T) /f _(W)>6.0  (b-1) ω_(W)≧30  (a-2) where, f₂ is a composite focal length of the second lens unit, f_(T) is a focal length of the entire system at a telephoto limit, f_(W) is a focal length of the entire system at a wide-angle limit, and ω_(W) is a half view angle (°) at a wide-angle limit.
 2. The zoom lens system as claimed in claim 1, wherein the second lens unit includes a lens element having positive optical power, and the following condition (5) is satisfied: 1.88<nd_(2p)<2.20  (5) where, nd_(2p) is a refractive index to the d-line of the lens element having positive optical power, which is included in the second lens unit.
 3. The zoom lens system as claimed in claim 1, wherein the second lens unit includes a lens element having negative optical power, and the following condition (6) is satisfied: 0.35<(r _(2na) +r _(2nb))/(r _(2na) −r _(2nb))<1.20  (6) where, r_(2na) is a radius of curvature of an object side surface of the lens element having negative optical power, which is included in the second lens unit, and r_(2nb) is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit.
 4. The zoom lens system as claimed in claim 1, wherein the second lens unit is composed of two lens elements, in order from the object side to the image side, including a lens element having negative optical power, and a lens element having positive optical power, and the following condition (7) is satisfied: −8.5<(r _(2nb) +r _(2pa))/(r _(2nb) −r _(2pa))<−3.5  (7) where, r_(2nb) is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit, and r_(2pa) is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the second lens unit.
 5. The zoom lens system as claimed in claim 1, wherein the first lens unit includes a lens element having positive optical power, and the following condition (8) is satisfied: −1.80<(r _(1pa) +r _(1pb))/(r _(1pa) −r _(1pb))<0.00  (8) where, r_(1pa) is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the first lens unit, and r_(1pb) is a radius of curvature of an image side surface of the lens element having positive optical power, which is included in the first lens unit.
 6. The zoom lens system as claimed in claim 1, wherein the following condition (9) is satisfied: 1.87<f ₃ /f _(W)<3.00  (9) where, f₃ is a composite focal length of the third lens unit, and f_(W) is a focal length of the entire system at a wide-angle limit.
 7. The zoom lens system as claimed in claim 1, wherein the following condition (10) is satisfied: 0.5<f _(3IL) /f ₃<1.5  (10) where, f_(3IL) is a focal length of the image side lens element having positive optical power, which is included in the third lens unit, and f₃ is a composite focal length of the third lens unit.
 8. The zoom lens system as claimed in claim 1, wherein the third lens unit includes a cemented lens element which is obtained by cementing the object side lens element having positive optical power with the lens element having negative optical power.
 9. The zoom lens system as claimed in claim 1, wherein the fourth lens unit comprises solely a lens element having positive optical power.
 10. The zoom lens system as claimed in claim 1, wherein the following condition (11) is satisfied: −1.00<f _(3n) /f ₃<−0.25  (11) where, f_(3n) is a focal length of the lens element having negative optical power, which is included in the third lens unit, and f₃ is a composite focal length of the third lens unit.
 11. An imaging device capable of outputting an optical image of an object as an electric image signal, comprising: a zoom lens system that forms an optical image of the object; and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein the zoom lens system is the zoom lens system as claimed in claim
 1. 12. A camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising: an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein the zoom lens system is the zoom lens system as claimed in claim
 1. 13. A zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and the following conditions (3-2), (b-1) and (a-2) are satisfied: 1.1<(β_(2T)/β_(2W))(β_(3T)/β_(3W))<5.2  (3-2) f _(T)/f_(W)>6.0  (b-1) ω_(W)≧30  (a-2) where, β_(2T) is a lateral magnification of the second lens unit at a telephoto limit, β_(2W) is a lateral magnification of the second lens unit at a wide-angle limit, β_(3T) is a lateral magnification of the third lens unit at a telephoto limit, β_(3W) is a lateral magnification of the third lens unit at a wide-angle limit, f_(T) is a focal length of the entire system at a telephoto limit, f_(W) is a focal length of the entire system at a wide-angle limit, and ω_(W) is a half view angle (°) at a wide-angle limit.
 14. The zoom lens system as claimed in claim 13, wherein the second lens unit includes a lens element having positive optical power, and the following condition (5) is satisfied: 1.88<nd_(2p)<2.20  (5) where, nd_(2p) is a refractive index to the d-line of the lens element having positive optical power, which is included in the second lens unit.
 15. The zoom lens system as claimed in claim 13, wherein the second lens unit includes a lens element having negative optical power, and the following condition (6) is satisfied: 0.35<(r _(2na) +r _(2nb))/(r _(2na) −r _(2nb))<1.20  (6) where, r_(2pa) is a radius of curvature of an object side surface of the lens element having negative optical power, which is included in the second lens unit, and r_(2nb) is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit.
 16. The zoom lens system as claimed in claim 13, wherein the second lens unit is composed of two lens elements, in order from the object side to the image side, including a lens element having negative optical power, and a lens element having positive optical power, and the following condition (7) is satisfied: −8.5<(r _(2nb) +r _(2pa))/(r _(2nb) −r _(2pa))<−3.5  (7) where, r_(2nb) is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit, and r_(2pa) is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the second lens unit.
 17. The zoom lens system as claimed in claim 13, wherein the first lens unit includes a lens element having positive optical power, and the following condition (8) is satisfied: −1.80<(r _(1pa) +r _(1pb))/(r _(1pa) −r _(1pb))<0.00  (8) where, r_(1pa) is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the first lens unit, and r_(1pb) is a radius of curvature of an image side surface of the lens element having positive optical power, which is included in the first lens unit.
 18. The zoom lens system as claimed in claim 13, wherein the following condition (9) is satisfied: 1.87<f ₃ /f _(W)<3.00  (9) where, f₃ is a composite focal length of the third lens unit, and f_(W) is a focal length of the entire system at a wide-angle limit.
 19. The zoom lens system as claimed in claim 13, wherein the following condition (10) is satisfied: 0.5<f _(3IL) /f ₃<1.5  (10) where, f_(3IL) is a focal length of the image side lens element having positive optical power, which is included in the third lens unit, and f₃ is a composite focal length of the third lens unit.
 20. The zoom lens system as claimed in claim 13, wherein the third lens unit includes a cemented lens element which is obtained by cementing the object side lens element having positive optical power with the lens element having negative optical power.
 21. The zoom lens system as claimed in claim 13, wherein the fourth lens unit comprises solely a lens element having positive optical power.
 22. The zoom lens system as claimed in claim 13, wherein the following condition (11) is satisfied: −1.00<f _(3n) /f ₃<−0.25  (11) where, f_(3n) is a focal length of the lens element having negative optical power, which is included in the third lens unit, and f₃ is a composite focal length of the third lens unit.
 23. An imaging device capable of outputting an optical image of an object as an electric image signal, comprising: a zoom lens system that forms an optical image of the object; and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein the zoom lens system is the zoom lens system as claimed in claim
 13. 24. A camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising: an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein the zoom lens system is the zoom lens system as claimed in claim
 13. 25. A zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and the following conditions (4-2), (b-1) and (a-2) are satisfied: 0.9<M ₁ /M ₃<3.0  (4-2) f _(T) /f _(W)>6.0  (b-1) ω_(W)≧30  (a-2) where, M₁ is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive), M₃ is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive), f_(T) is a focal length of the entire system at a telephoto limit, f_(W) is a focal length of the entire system at a wide-angle limit, and ω_(W) is a half view angle (°) at a wide-angle limit.
 26. The zoom lens system as claimed in claim 25, wherein the second lens unit includes a lens element having positive optical power, and the following condition (5) is satisfied: 1.88<nd_(2p)<2.20  (5) where, nd_(2p) is a refractive index to the d-line of the lens element having positive optical power, which is included in the second lens unit.
 27. The zoom lens system as claimed in claim 25, wherein the second lens unit includes a lens element having negative optical power, and the following condition (6) is satisfied: 0.35<(r _(2na) +r _(2nb))/(r _(2na) −r _(2nb))<1.20  (6) where, r_(2na) is a radius of curvature of an object side surface of the lens element having negative optical power, which is included in the second lens unit, and r_(2nb) is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit.
 28. The zoom lens system as claimed in claim 25, wherein the second lens unit is composed of two lens elements, in order from the object side to the image side, including a lens element having negative optical power, and a lens element having positive optical power, and the following condition (7) is satisfied: −8.5<(r _(2nb) +r _(2pa))/(r _(2nb) −r _(2pa))<−3.5  (7) where, r_(2nb) is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit, and r_(2pa) is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the second lens unit.
 29. The zoom lens system as claimed in claim 25, wherein the first lens unit includes a lens element having positive optical power, and the following condition (8) is satisfied: −1.80<(r _(1pa) +r _(1pb))/(r _(1pa) −r _(1pb))<0.00  (8) where, r_(1pa) is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the first lens unit, and r_(1pb) is a radius of curvature of an image side surface of the lens element having positive optical power, which is included in the first lens unit.
 30. The zoom lens system as claimed in claim 25, wherein the following condition (9) is satisfied: 1.87<f ₃ /f _(W)<3.00  (9) where, f₃ is a composite focal length of the third lens unit, and f_(W) is a focal length of the entire system at a wide-angle limit.
 31. The zoom lens system as claimed in claim 25, wherein the following condition (10) is satisfied: 0.5<f _(3IL) /f ₃<1.5  (10) where, f_(3IL) is a focal length of the image side lens element having positive optical power, which is included in the third lens unit, and f₃ is a composite focal length of the third lens unit.
 32. The zoom lens system as claimed in claim 25, wherein the third lens unit includes a cemented lens element which is obtained by cementing the object side lens element having positive optical power with the lens element having negative optical power.
 33. The zoom lens system as claimed in claim 25, wherein the fourth lens unit comprises solely a lens element having positive optical power.
 34. The zoom lens system as claimed in claim 25, wherein the following condition (11) is satisfied: −1.00<f _(3n) /f ₃<−0.25  (11) where, f_(3n) is a focal length of the lens element having negative optical power, which is included in the third lens unit, and f₃ is a composite focal length of the third lens unit.
 35. An imaging device capable of outputting an optical image of an object as an electric image signal, comprising: a zoom lens system that forms an optical image of the object; and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein the zoom lens system is the zoom lens system as claimed in claim
 25. 36. A camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising: an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein the zoom lens system is the zoom lens system as claimed in claim
 25. 